Dynamic V isualizations Chemistry Courses
Jerry P . Suits * , 1 and Michael Sanger 2
1 Department Chemistry & Biochemistry , University Northern Colorado, eeley , Colorado 80639
2 Department Chemistry , Middle T ennessee State University , Murfr eesbor T ennessee 37132
* E - mail: jerry .suits@unco.edu
Chemistry can a very dif ficult topic for students part because requires students think abstractly about the behaviors and interactions atoms, and V isualizations chemistry can help make chemistry the particulate level less abstract because students can actually these and dynamic visualizations can help students understand how these particles interact and change over time a reaction This chapter provides a brief description molecular - level interactive chemistry simulations, and chemical systems and interactive this chapter includes a brief summary the subsequent chapters this book, which are divided into four dif ferent categories: Theoretical aspects visualization design, design and evaluation visualizations, visualizations studied chemical education and visualizations designed for the chemistry classroom.
Intr oduction
Chemical educators have long recognized that students have dif ficulty learning chemistry concepts ( 1 – 4 ) . Some the reasons put forth explain this dif ficulty include the ideas that: (a) Chemistry involves very abstract ideas that are not easily seen understood ( 1 – 4 ) , (b) Solving chemical problems often require students access and process many dif ferent concepts and data the same time ( 4 – 6 ) , (c) order successful understanding chemistry concepts, students must able think and convert between the macroscopic,
particulate (sometimes called the molecular , and symbolic levels representation ( 3 – 5 , 7 – 9 ) , and (d) Students learning chemistry often have strongly - held preexisting conceptions that are inconsistent with scientifically - accepted theories and can interfere with subsequent learning ( 3 , – ) .
Most visualizations ( – ) designed for chemistry instruction involve depictions atoms, molecules, and / ions and their interactions (the particulate either static images dynamic visuals including both animations ( ) and simulations ( ) . The advantage particulate visualizations (static dynamic) the chemistry classroom that they provide students with a view the behavior and interactions between the chemical particles, which are often abstract and dif ficult for students generate their these visuals help make the abstract interaction and ions more concrete ( 3 , , ) , and can lower the cognitive load placed the chemistry student ( 4 , 5 , , ) . with proper these visuals can help students make connections between the macroscopic, particulate, and symbolic representations ( , , ) , which can lead more scientific conceptions the part the chemistry student ( – ) . Since many chemistry concepts require students understand how the chemical systems change over time reactants vs. products, before - and - after gas law experiments, equilibrium reactions, etc.), showing dynamic visuals can especially helpful for Rieber ( ) noted that dynamic computer animations were generally useful students studying science, but can distracting (and diminish learning) the lesson does not involve trajectory . Both animations and simulations can viewed student - centered forms instruction ( ) , which can support student learning they develop a conceptual understanding chemistry Some the issues fecting abilities learn chemistry concepts involve chemical theories misconceptions related the Kinetic Molecular Theory V alence Bond Theory ( ) ] and chemical education theories [e.g., the interrelationships between and symbolic representations ( 8 ) However , some these other issues are related psychology cognitive learning theories Constructivism ( 2 ) Cognitive Load Theory ( 6 ) ] theories the optimal design and usage multimedia programs ( , ) . Therefore, the design and use dynamic visualizations should take into account these and other chemical psychology / and multimedia theories. addition, dynamic visualization designers may want focus the issues student learning prior student interactivity and control, and assessments activities that will transcend mere recall while allowing students develop their own mental name but a few .
Molecular - Level Animations
According W ikipedia (https: / / g / wiki / animation rapid display a sequence static images and / objects create illusion movement.” Computer animations depicting chemical processes the molecular level have been studied for almost two decades
( , – ) , and have been shown have promise improving conceptual particulate - level understanding chemistry ( ) . Most these animations fall into one two categories ( ) : esentation animations (used present new information elaborate previously - presented information) conceptualization animations (used develop conceptual understanding without providing new Although molecular - level animations have been shown improve student learning chemistry , these animations can also lead new student misconceptions that were not present before viewing these animations ( , , , ) and can prove distracting students when the concepts that students are supposed learning are not visual nature ( ) not involve dynamic concepts such visualization, motion, trajectory ( ) . Because many these molecular - level animations were designed present new information chemistry they often require only passive user inputs while simulations tend emphasize a greater degree student interactivity .
Interactive Chemistry Simulations
A simulation uses a mathematical logical model recreate a situation phenomenon. allows the student control the interactivity the dynamic elements the phenomenon being studied ( ) . When a simulation uses low levels interactivity , students can control its instructional pace. This allows them understand one part before going the next one. W ith high - level interactivity , the student can control the behavior the simulation ( ) . students may input information (independent variables) establish a system acid - base system) before they are exposed the outcome (dependent variable). The outcome thus a consequence their decisions, which can represented a verbal mathematical a static a dynamic visualization (animation). The goals a simulation may include (a) help students accurately estimate the likelihood various outcomes; (b) deliberately focus their attention one part reality the expense other parts; (c) see help students see how a system works changing values for each and then the simulation”. The combination these three goals allows students make predictions about the behavior the system and receive feedback about how the system When students are given the proper level instructional support, they can use a properly designed simulation discover scientific concepts ( ) there a substantial amount support provided guide the student, then the simulation focused the guided discovery Conversely , when very little support the simulation design allows the student learn freely the pure discovery method ( ) .
Chemical Systems and Interactive Simulations
Most the chapters this book refer a chemical system , either explicitly implicitly interactive simulation allows students opportunity explore chemical systems because they can manipulate various parameters the system and then see the consequences their One definition a chemical system group interacting chemical species that exist a
dynamic relationship within a physical / chemical condition that responds a predictable manner changes both internal and external ( ) . One pedagogic value students modeling and simulating chemical systems that their learning can progress from misconceptions (pre - conceptions developed from past experiences that are incompatible with the scientifically - accepted models and that are often very resistant change) towards the scientific models that chemists have developed ( 9 ) . The goal help students progress the direction becoming who have developed the ability and predict the properties and behavior matter (p. 188)” ( 9 ) complex chemical interactive simulations allow students explore and begin truly understand chemical systems.
Overview the Chapters This Book
T able I contains a summary each chapter this book including the the types theoretical frameworks used, the types research methods used, a description classroom applications, and the chemistry topics addressed these
Theor etical Aspects V isualization Design
Chapters 2 - 4 this book focus theoretical issues and concerns developing and using animations and simulations teach chemistry concepts. The theoretical frameworks described these chapters not only include learning theories [such Behaviorism ( ) , Cognitive Load Theory ( 6 ) , and V s Zone Proximal Development ( ) but also describe design principles that are informed educational research learning with multimedia ( , ) . Both these frameworks can used improve the way dynamic visualizations are designed, created, and utilized the chemistry classroom.
Stief f and R yan (Chapter used three theoretical frameworks based cognitive learning theories explore how molecular visualizations can link how students learn the design dynamic This novel perspective the theory - research - practice triad explores the ways that (a) short - term memory works using both visual and auditory sensory information, (b) students acquire bits knowledge that can integrated initiate their conceptual understanding chemistry , and (c) visualizations can encourage students interact with each other molecular visualizations should designed focus the chemistry’, which the relationship between chemical structures and reactivity the molecular When students explore this they are representations unseen phenomena. While this chapter appeals mostly simulation designers and chemical education could also appeal chemistry instructors who want understand how the psychological mechanisms understanding chemistry relate visual representations chemical processes.
Homer , and Plass (Chapter describe the results a decade work the design, evaluation, and implementation interactive multimedia simulations kinetic - molecular theory aimed high school
The design these simulations focused presenting information that would not result cognitive overload the users (information design), where users had control the simulations but with guidance optimize their use (interaction interactivity design), and using instructional supports like worked - out examples and instructional strategies support reflection and student - student interactions (instructional tools and support). The authors also describe how these simulations were designed help students develop mental models with strong connections between the macroscopic, particulate, and symbolic representations. The description the decades work done create and evaluate these simulations should very useful simulation designers and chemical education well chemistry instructors who use may want use simulations such those described this chapter .
Gregorius (Chapter gues that the use learning theories guide the development and usage animations chemistry will lead more fective animations and improved student learning. Gregorius describes how used a variety learning theories develop and classroom - test chemistry animations with diverse populations students enrolled general chemistry courses over recent found that instruction including the use animations aligned lesson objectives, peer discussion, and formal reporting procedures led improved student grades. Gregorius describes examples animation designed based behaviorist learning theory assist students learning the names inor ganic compounds and animation designed based cognitivist learning theory (schemata development and situated learning) assist students investigating the relationships between pressure, volume, amount gas, and temperature under ideal gas This chapter should appeal simulation designers, chemical education researchers, and anyone who interested understanding the interconnections between learning theories and fective chemistry animations.
Design and Evaluation V isualizations
Chapters 5 - 8 this book provide two examples paired which the first chapter introduces and describes how the dynamic visuals were designed and created for use chemistry instruction and the second chapter describes a chemical education research study performed evaluate the fectiveness using these dynamic visuals for chemistry instruction. Chapters 5 and 6 focus interactive simulations created part the PhET Interactive Simulations Project. Chapters 7 and 8 focus the virtual - world program Second Life and how being used teach chemistry
Lancaster , Moore, Parson, and Perkins (Chapter have developed and classroom - tested over 125 PhET interactive simulations order promote student conceptual understanding science general, and chemistry particular . Their design was guided three areas research how people chemical education research how students
understand chemistry , and research design features informed educational technology and psychology . These simulations provide student interactivity and dynamic feedback support students the process creating, controlling and understanding virtual chemical The authors noted three issues related the creation simulations that were unique the field chemistry: Explaining macroscopic behavior terms particle representing physical processes terms symbolic and particulate representations, and using real - world examples identify trends and develop This chapter could appeal simulation designers, chemical education researchers, and chemistry instructors interested using these (or similar) simulations their classrooms who would like see how simulations can designed and used help students explore and make sense complex chemistry
Akaygun and Jones (Chapter used a PhET simulation solubility equilibria investigate how the degree interactivity animation simulation fected the mental and perceived cognitive load the dynamic visuals for high school and college students. They found that students used molecular features more often their descriptions and mental models after they had experienced the its degree interactivity For the two groups attitudes and perceptions the cognitive load needed use the animation simulation were not significantly dif The researchers found that there was a negative correlation between perceived cognitive load the visualization (whether not the amount information presented overwhelmed their ability process it) and scores the conceptual post - test solubility This chapter should interest anyone interested the relative fectiveness animations with little student control versus simulations with more student control—designers, researchers, and chemistry instructors.
W inkelmann (Chapter describes how virtual laboratory experiments are well suited for college chemistry courses and presents preliminary results a study where chemistry students performed a virtual chemistry experiment within Second Life , popular virtual world program that allows virtual people and objects The students create a virtual representation themselves (an avatar) that can move objects and interact with other Students can then perform a virtual experiment with the chemicals and equipment provided The experiment analogous a real experiment acids and bases react with each other) but the danger the chemistry laboratory negative consequences should established the virtual world correspond real dangers. W inkelmann gave his students a pre - lab quiz and required them analyze their virtual data and turn a real lab While his students enjoyed the experience, they favored working with real chemicals. This chapter would interest anyone interested either supplementing the real laboratory replacing it, provided that they understood the consequences doing so.
Kenney - Kennicut and Merchant (Chapter evaluated how performing several molecular creation and manipulation activities the virtual world Second Life fected understanding the topic VSEPR theory and the 3 - D nature molecules compared students who worked with 2 - D screen shots taken from SL. The two groups students showed significant dif ferences
content logical thinking and visualization abilities after the experiment took place. Further analysis showed that the group exhibited increased ability interpret routine 2 - D presentations 3 - D chemical structures, although many students both groups could not interpret the 3 - D information presented 2 - D drawings molecules. Although they found potential benefits student attitudes the group were split with regard the potential benefits use chemistry courses. This chapter would special interest anyone who concerned with the potential benefits synchronous (all students learning the same time) asynchronous (same lesson but performed dif ferent times) such use quizzes and interactions with virtual chemical species.
V isualizations Studied
Chemical Education Resear chers
Chapters 9 - this book describe the results chemical education research studies the use animations and The research presented Chapters 9 and focused evaluating the instructional fectiveness 9 looked instructor perceptions a way design instructional scaf folds with the ultimate goal improving student learning from while Chapter evaluated how the use a simulation fects content knowledge and mental models. The research presented Chapters 1 1 - compared how dif ferent instructional conditions fected chemistry content knowledge and other cognitive skills. Chapter 1 1 looked the fect using 3 - D visualizations and active learning strategies (compared 2 - D static pictures and passive learning techniques) content knowledge and their ability think and create guments the particulate Chapter compared the content knowledge and mental rotation ability students creating particulate pictures using a 3 - D animation program a series 2 - D note cards. Chapter compared the particulate - level explanations students viewing a more simplified animation followed a more complex animation the same chemical reaction the explanations students viewing these two animation the opposite order . Chapter consisted two research studies; one comparing how a single group students interacted with a simulation including a dynamic analogy - based depiction, and one comparing how a group students viewing the dynamic analogy performed compared a group students which the dynamic analogy was Kelly (Chapter studied how chemistry instructors conceptualize chemical phenomena the atomic / molecular Her rationale for conducting this study was that instructors serve the interface between visualization designers (by selecting and using particular products) and their students (by providing a classroom context where visualizations phenomena can linked She found a great variety the the which spanned from using key features show simplistic representations those exhibiting more updated and complex scientific conceptions the molecular phenomena. The former allows students bridge from one level understand another , while the latter more likely ensure accuracy . These findings may relate how much instructional support (scaf folding) students need understand
This chapter could appeal chemistry instructors who can see that their advise being solicited and used, researchers who study the fectiveness instruction using visualizations, and simulation designers whose work can improved through the use this vital Suits and Srisawasdi (Chapter 10) studied how the use interactive simulation they created fected content knowledge and mental models related hydrogen bonding water . The simulation used instructional scaf folds help students relate the macroscopic property contact angle water the particulate property hydrogen bonding forces. They found that (prior instruction) low medium and high - achieving students had dif ferent content knowledge (low < medium < high), dif ferent particulate - level mental models (low
≈ medium < and similar macroscopic - level mental models (low ≈ medium
≈ After using the interactive each set students showed significantly improved content knowledge and particulate - and macroscopic - level mental but the initial dif ferences these three groups did not For the particulate - level mental models, each group showed fewer misconceptions and more correct conceptions after using the This chapter should interest simulation designers and chemical education researchers example how evaluate the fectiveness a chemistry and chemistry instructors thinking about using simulations their classrooms. Barak (Chapter 1 performed three experiments using students dif ferent educational levels study the fect actively interacting with 3 - D dynamic visualizations compared passively viewing 2 - D static drawings. The first study used animated movies explain scientific concepts elementary students, the second study used 3 - D molecular visualizations teach high school students about the structure - function relationship and the third study asked college students use 3 - D molecular visualizations help writing weekly reports about the structure and usage This study showed that students actively using the 3 - D visualizations showed greater conceptual understanding; greater ability convert between 2 - 3 - and textual representations; greater ability convert between macroscopic, particulate, symbolic, and process representations; and stronger molecular explanations and guments with respect their peers using the 2 - D static This study could appeal simulation designers and educational researchers, but should special interest elementary and high school teachers a model fective ways incorporate a combination dynamic visualizations and active learning strategies their W illiamson, W atkins, and W illiamson (Chapter 12) compared the chemistry content mental rotation ability , and attitudes students who were asked model physical and chemical equilibrium reactions using either animation program (ChemSense) a series note They found that both groups students showed improvement their content knowledge physical and chemical equilibria and their mental rotation ability; however , these scores were not significantly dif ferent when the two groups students were One possible explanation for this lack dif ference was that many students using the note cards tended create a step - - step series pictures that lar gely resembled animation. This study also found that male students showed better
mental rotation abilities than female and males showed a lar ger increase their mental rotation abilities after the study compared females. Although this study should interest animation designers and chemical education should especially interesting chemistry instructors since shows that students who create visuals using animation program note cards can improve their chemistry content knowledge and spatial thinking Rosenthal and Sanger (Chapter 13) investigated whether the sequence viewing two animations the same chemistry topic (oxidation - reduction reactions) should proceed from simplified complex vice versa. Learning theories and common sense could gue for either these sequences because both are representations molecular phenomena. The authors found that the complex - - simple sequence animations led improved student understanding this complex chemical This sequence appeared use the more complex animation grab attention, then showing the simpler one helped students explain the chemical When students viewed both they had dif ficulty relating the concepts depicted one animation the other because the same chemical species (copper / silver copper / silver were often depicted dif ferent ways. The role water this reaction was somewhat confusing just a spectator , active participant the chemical reaction, the driving force the reaction? This chapter should interest anyone who wonders about the instructional fectiveness animations—designers, researchers, and chemistry instructors. Khan (Chapter 14) performed two studies determine how a multifaceted simulation equilibrium system using a two - pan balance a dynamic analogy the equilibrium process can improve student understanding chemical one study , she evaluated understanding equilibrium concepts after they had viewed the analogy - based simulation. After viewing the students showed a partial improvement the understanding the behavior molecules before and right after a chemical added disturb but still had dif ficulty describing the distribution and composition the particles after equilibrium was reestablished. The other study compared conceptual understanding Chatelier ’ s principle after using the simulation either with the dynamic analogy enabled Khan found that students viewing the simulation with the dynamic analogy enabled had a better understanding Chatelier ’ s principle than those viewing the simulation without the dynamic analogy . This chapter may especially appeal chemistry instructors who are interested how teach chemical systems because gives elaborate example visualizations that were studied and used chemistry
V isualizations Designed for the Chemistry Classr oom
Chapters - describe how specific dynamic visualization programs and modules were designed and how they should utilized the chemistry classroom improve student learning. Chapter describes the steps used create analogy - based animations for the chemistry classroom and describes a couple examples related kinetics and Chapter describes
visualizations based modeling ganic reaction mechanisms and viewing 3 - D models biomolecules. Chapter describes the process creating and the optimal use several simulation modules focusing the chemistry concepts related global climate
Ashe and Y aron (Chapter 15) gue that appropriately designed simulations incorporating analogies involving everyday objects can help students learn abstract concepts needed ganize their content knowledge. They describe the steps used create these analogies which the simpler more familiar situation (base) mapped onto the more complex abstract concept (tar get). example discussed this chapter the use cardboard box (and its relative stability with respect its center gravity) serve analogy for the reaction - coordinate diagram used for chemical They also describe another analogy explain the relative populations (based the ener gies) the activated and product states using a container filled with balls containing tiers dif ferent heights placed a vibrating This chapter should extremely valuable chemistry teachers who are looking for new and interesting ways teaching chemistry concepts their students using simple analogies a way improve conceptual understanding.
Fleming (Chapter 16) provides historical description and analysis the advantages and disadvantages several visualization programs created teach two topics that students often have dif ficulty ganic reaction mechanisms and visualization 3 - D biomolecules. Included this summary a description a multi - representational animation S N 2 reaction that synchronizes changes structure from the reactant the transition state the product with the progress - - reaction graph (reaction - coordinate diagram). This animation allows the student stop study and carefully watch this inversion mechanism a way truly understand it. The 3 - D biomolecular animations described the chapter provide biochemistry students with a 3 - D perspective that allows students rotate these molecules order understand their structure - function This chapter would especially valuable ganic chemistry instructors who recognize that students need help visualizing ganic reaction mechanisms, and biochemistry instructors who would like their students complex the 3 - D structures
Martin and Mahaf (Chapter 17) describe the rationale used create a set simulations within the rich context the complex chemical systems present global climate change, and describe detail how these modules can used the chemistry The interactivity and feedback these simulations allowed the authors monitor and assess student misconceptions related this real - world These interactive simulations were embedded chemistry course content foster student engagement more interactive ways probing evidence and constructing mental models built upon fundamental science concepts). The authors point out that scientists who study the science global climate change use simulations that are based real - world data from atmospheric students are learning from pedagogic simulations using the same real - world data that scientists use construct scientific models climate This chapter should interest chemistry instructors who recognize the value real - world chemistry applications, simulation designers
who seek examples embedding simulations a complex chemistry and chemical education researchers who want study simulations within a complete instructional
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Intr oduction
V isualizations are increasingly prevalent secondary and post - secondary chemistry classrooms where they ford students greater access the central concern chemistry , namely structure and reactivity ( 1 ) . The advancement new educational technologies presents unprecedented opportunities for educators provide students with access visual representations atomic structures, molecular interactions, and lar datasets support chemistry T oday , students and teachers all levels instruction employ a wide array visualizations that allow them conduct that demonstrate physical and chemical The benefit such tools for improving the learning chemistry appears self - evident: because these tools provide visual representations the unseen phenomena study , students who use them will develop a richer and more accurate understanding chemistry concepts.
V isualizations have seen increasing use the classroom; however , evidence their fectiveness for improving learning and understanding has been unreliable ( 2 ) Relatively few studies have demonstrated that these new technologies produce reliable gains student engagement, achievement, retention, fect. some students who learn from visualizations achieve higher scores summative assessments than students who not use visualizations ( 3 , 4 ) ; visualizations produce gains (or even decrements) achievement ( 5 , 6 ) . The discrepancy these findings raises important questions about the underlying mechanisms that explain the ficacy visualizations for teaching chemistry specifically . this chapter , gue that unreliable reports the ficacy visualizations, specifically animations and simulations, are artifacts studies that include unprincipled implementations visualizations learning environments that not instantiate rigorously tested design principles. Current approaches the design and study visualizations chemistry make use two major theoretical frameworks developed within the chemistry education research (CER) community Although these frameworks are often conflated, they are dif ferent kind. First, chemistry education researchers have long gued that students face significant challenges coordinating the and symbolic descriptive the domain ( 7 – 9 ) Citing such challenges the central obstacle for learning the discipline, many designers have constructed new visualizations that present multiple levels simultaneously ( ) . According this framework, visualizations are fective because they relieve the student from the burden identifying the relationship between multiple levels. Second, chemistry education researchers gue that chemistry dif ficult learn because students must coordinate the meaning multiple representations ( 1 1 , ) . Multiple symbolic representations, such empirical formulas and structural are used refer the same submicroscopic entities, and students not clearly perceive the relationship among all available representations. T o address this issue, designers have built new simulations that present linked representations simultaneously ( ,
) According this the ficacy visualizations results from interfaces that help students relate representations.
Although the application these two frameworks has yielded important insights into the design chemistry they are both limited their power explain how and why visualizations can promote chemistry learning across the curriculum more broadly . A more comprehensive account the role visualizations needed realize their full potential the chemistry classroom. aim stimulate discussion about the role visualizations and the design research programs that investigate their ficacy . T o that end examine three which are widely employed the communities cognitive and learning scientists, that can account for the underlying mechanisms learning with visualizations general and provide specific predictions about the design learning environments that make use chemistry Importantly , these models are based empirical data student learning and motivate design principles that give systematic structure visualization interfaces and learning activities. such, each leads strong recommendations about when and why visualizations are fective various
What a Chemistry isualization?”
V isualizations chemistry take many forms, and the word has been used multiple ways throughout the chemistry education research literature ( 1 , – ) For the sake this chapter , are restricting our use the term visualization any virtual envir onment that r epr esents dynamic interactions submicr oscopic (or subatomic) phenomena . W e have restricted our definition this way because prior research indicates that a primary challenge learning chemistry involves mechanistic reasoning chemistry ( ) . That is, struggle understand how particle behavior ( ) a lesser structure ( ) are related the chemical and physical properties substances. technologies that include visual representations particle and interaction hold the most promise for helping students develop a coherent understanding particle behavior . W e acknowledge that many chemistry visualizations may include representations other descriptive levels phenomena, such macroscopic pictures symbolic representations ( ) ; however , believe these technologies not facilitate mechanistic reasoning like submicroscopic visualizations.
A significant consequence our definition that exclude visualizations that demonstrate simulations macroscopic experimental techniques ( ) facilitate the memorization dif ferent symbols the chemistry classroom ( ) This definition also excludes submicroscopic simulations that allow manipulation chemical structures without showing dynamism, such electrostatic potential maps ( ) Jmol ( ) . Our intent not diminish the relevance these types
visualizations for learning chemistry T o the contrary , believe that these types environments can fective a variety contexts, but the underlying models that motivate their use are dif ferent from those models that discuss this paper .
Excluding visualizations these kinds, note that our definition captures several learning environments widely employed secondary and under graduate classrooms that have been produced the CER community ( Figure 1 such PhET simulations ( ) , V isChem ( ) , Molecular W orkbench ( ) , Electr onic Learning T ools ( ) , and The Connected Chemistry ( ) . Notably , these learning environments fer visualizations dif ferent such animations and simulations. Animations include those visualizations that display a scripted sequence events for passive These visualizations often permit students set initial set conditions and limit the displayed information highlight only those features most relevant the represented concept. Animations can fective tools direct students focus their attention a specific aspect a phenomenon the submicroscopic level, such the process dissolution ( ) simulations use empirical data and algorithms display dynamic interactions resultant from particle motion real time ( , ) . T oday , many simulations allow students exercise greater agency than animations including interfaces that allow manipulation system variables and control a microworld where they can construct virtual experiments test predictions a virtual environment that has a high degree fidelity the physical world ( ) .
Designers embed animations and simulations learning environments that can dif fer five dimensions: contr , interactivity , feedback type , feedback amount , and r epr esentational consistency ( , ) . Contr refers the extent which a student can set initial system parameters and explore the visualization ways their own choosing. Interactivity refers the extent which a designer provides the student with opportunities influence the behavior the system real time. For example, two simulations from The Connected Chemistry Curriculum , Real Ideal Gas and Chemical Changes , dif fer both interactivity and control. Both simulations were designed a microworld that uses a physics engine that updates the position and velocity each particle dynamically and probability models determine the outcome particle collisions real the Real Ideal Gas simulation ( Figure 2 students have little control over the microworld: the only variable that the designers allow the students manipulate determines whether the simulation models ammonia a real gas ideal Similarly , students can interact with the simulation only one way the simulation runs, they can toggle between real and ideal gas behavior . the Chemical Changes simulation ( Figure 3 ) highly interactive includes multiple variables (e.g., volume, heat, and mass) that students can manipulate real students modify system the simulation updates and displays changes dependent variables. Because students are able select many possible starting conditions and modify how the simulation runs they students are able exercise more control over their learning running many dif ferent simulations that have unique parameters. V isualizations this kind give students more agency over their learning chemistry .
Figur e 1 . Examples extant animations and simulations oduced the chemistry education r esear community . Scr eenshots
Electr onic Learning T ools Atomic Level V iew animation (Courtesy Electr onic Learning T ools (www .chemteam.net)), Molecular W orkbench States Matter simulation (Courtesy The Concor d Consortium (http: / / concor d.or g). Molecular W orkbench simulations can found http: / / .concor d.or g.), The Connected Chemistry Curriculum Mixtur simulation (Courtesy The Connected Chemistry Curriculum (www .connchem.or g)), PhET Salts & Solubility simulation (Courtesy PhET Interactive Simulations the University Colorado. PhET simulations can found http: / / phet.colorado.edu) and V isChem Chemical Reactions Complexation animation (Courtesy V isChem). (see color insert)
on September 22,
Figur e 2 . A scr eenshot The Connected Chemistry Curriculum Real vs. Ideal Gas simulation that offers a low level interactivity and offers students limited contr the variables. Courtesy The Connected Chemistry Curriculum (www
Figur e 3 . A scr eenshot The Connected Chemistry Curriculum Chemical Changes simulation that highly interactive and offers students contr several Courtesy The Connected Chemistry Curriculum (www
Feedback type refers the quality feedback users receive about the appropriateness their interactions and the results their choices when working a This feedback can explicit when the interface fers clear and direct evaluative information the student; alternatively , feedback can implicit when the interface only indirectly provides such information. Feedback amount refers how often a user presented with V isualizations can provide users with limited extended feedback. T aken together , the type and amount feedback can range from limited and implicit extended and
For example, the PhET Build a Molecule simulation fers limited and implicit feedback prohibiting students from building incorrect When a student tries create ener getically unfavorable bond between two atoms, the simulation responds forcing the two atoms explicit feedback provided that explains why the bond does not why two atoms were forced apart, guidance a correct solution.
Alternatively , the Electr onic Learning T ools Atomic Level V iew animation fers students extended, explicit feedback while interacting with the interface. shown Figure 4 a , students are presented with responses they produced prior working with the animation and asked reflect upon those responses after viewing The students are then prompted construct a new image represent how their understanding has changed. When a student constructs incorrect diagram incorrect ratio lack the interface prompts the students with questions help the students construct accurate diagram. For example, Figure 4 b , the ratio sodium ions chloride ions incorrect and the question the ratio between the sodium and chloride the appears. Importantly , some learning environments not provide feedback the visualization itself and instead rely teachers other curricular materials provide feedback.
Lastly , r epr esentational consistency refers the extent which a microworld makes systematic use a system representations that link the visual images displayed the objects and phenomena they Electr onic Learning T ools, ChemV and The Connected Chemistry Curriculum all demonstrate a high degree representational consistency assigning a specific size and color each element the periodic For water molecules both learning environments are represented with two white balls (hydrogen atoms) and one red ball (oxygen a student can anticipate that any red ball any visualization refers oxygen atom. contrast, PhET simulations and Molecular W orkbench visualizations demonstrate a low degree representational consistency . For example, Molecular W orkbench water represented two white circles (hydrogen atoms) attached another red circle (oxygen atom) the
Solubility: Dissolving Salt W ater animation ( Figure 5 a but a generic two atom polar molecule the Intermolecular Attractions and Solubility animation ( Figure 5 b
Figur e 4 . Scr eenshot the Electr onic Learning T ools animation feedback Students e ompted r eflect their econception after watching animation Students e given explicit feedback the form ompting questions when incorr ect configurations have been selected. Courtesy Electr onic Learning T ools (www
Figur e 5 Examples r epr esentational inconsistency Molecular W orkbench visualizations. Elements and molecules e r epr esented differ ent between Courtesy The Concor d Consortium (http: / / concor Molecular W orkbench simulations can found http: / / .concor d.or
Thr
Explanatory Models for the Efficacy Chemistry V isualizations
W ith a working definition a and a list features common several learning environments that employ next review three models human learning that believe can inform design and research the ficacy First, examine the potential visualizations support retention domain concepts according the tripartite model
working memory ( , ) explore the potential visualizations for promoting conceptual understanding when embedded lessons using the contemporary - - model conceptual change ( , ) Finally , review the potential visualizations for supporting social interactions chemistry using one model social cognitive learning ( , ) W e believe these models permit the CER community extend their work visualizations beyond simple assumptions that visualizations are fective because they help students molecules and atoms that are otherwise invisible the naked eye. Each model supports a discrete set research questions that warrant investigation the context chemistry instruction; together , the models fer a conver gent set design principles for building new visualizations. course, beyond the scope this chapter review each model extensive Rather , our hope that overview these theories will spur the chemistry education research community seek ways apply these models their work produce more innovative designs and more rigorous empirical studies that establish the fectiveness visualizations.
The T ripartite Model W orking Memory
The first model review Baddeley & s tripartite model working memory ( , , ) The tripartite model working memory one several information processing models proposed cognitive scientists explain human memory Information ocessing models are cognitive models that attempt describe the ganization and structure memory and the processes which information transferred and transformed within and between these The first these models was put forward the late 1950s attempt explain complex learning and information recall, and several models have been proposed, and abandoned over the past years ( , ) . Importantly , the central concern these theories explain how humans acquire, retain, and recall information that experienced the world (as opposed generated the The rise information processing models the 1950s was coincident with the rise computing technologies the The success hardware that partitioned information among hardware components that stored information for long - term retention one component the hard drive) and components that retrieved and manipulated that information execute programs RAM), fueled theoretical models that included similar partitioned components the human There much debate about whether cognitive s information processing models mind computer s hardware architectures were developed first; however , the cognitive science community agreed that regardless which field predates the other , the two grew tandem ( ) Advancements one area led insights the other engineers and psychologists collaborated design hardware components that better simulated human problem solving and provided a test bed for experiments aimed furthering our understanding human memory . Among the various models still employed cognitive scientists and learning scientists today are the ( ) , the model
( ) , and the model working ( ) Researchers various disciplines employ each these models explain how students remember disciplinary concepts and apply those concepts for problem Although each theory maintains unique descriptive models human memory , all share a common commitment underlying structure that involves the storage and activation mental representations Although Atkinson and Shrif s model did not rigidly define the structure memory , the later models posited that human memory divided into multiple components that include the sensory r egister , working memory , and long - term memory . Briefly , the sensory register responsible for filtering information the world and translating that information into mental representations that can manipulated and stored for later W orking memory responsible for manipulating mental representations for problem solving and executing processes that transfer these representations into and out long - term memory . Finally , long - term memory responsible for the storage mental representations for retrieval and later use.
There are important dif ferences among the information processing models with regard the cognitive architecture and the information handling processes responsible for the and retrieval Cognitive scientists not consider the models equivalent, and each model leads dif ferent predictions about learning and human behavior Increasingly , research neuroscience supports component models with evidence that specific neural structures are responsible for storage and processing dif ferent stages Between the component believe that Baddeley and s tripartite model working memory provides the most fruitful explanations the fectiveness animations and simulations and fers a sound theoretical framework support further research the ficacy new visualizations chemistry Baddeley and s model ( , ) the foundation for several contemporary learning theories, such Mayer ’ s ( ) Theory Multimedia Learning Sweller ’ s ( ) Cognitive Load Theory , which have been used explain the ficacy educational technologies more broadly . Although these later two theories have found much traction the chemistry education research community , believe that the community might benefit from a first principles.” These contemporary theories fer clear explicit principles (e.g., design interfaces that not require students read text simultaneously while viewing animation ( ) however , the underlying mechanisms which visualizations can improve retention and recall best explained the original tripartite model working memory . Similarly , believe that research that makes use the tripartite model working memory can produce more precise recommendations about which concepts are suited for learning via animations and our hope that a review the model can motivate new discussions among chemistry educators about how best design new interfaces and analyze the relative fordances those designs.
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“Keep down,” Gerry begged of her “Keep down behind the engine!”
“You!” she murmured to him. “I thought when I saw you in the air and when you fought them so, that it might be you! Where are you hurt; oh, how much?”
“Not much; I don’t know where, exactly. Keep down behind the engine, Cynthia!”
She was not hurt at all, he saw; and though the tangle of wires enmeshed his legs, he was able to turn about and seize her and press her down lower. For the machine gunner was spraying the wreck of the airplane now. She was working with her strong little hands, trying to untwist and unloop the wires to get him free when Gerry heard the motor noises of an airplane, descending. He gazed up and saw a German machine swooping a thousand feet above the ground. The pilot passed over them and, diving, came back five hundred feet lower; he took another look, circled and returned barely a hundred yards up. This time he would fire, Gerry knew; and it was impossible to find shield at the same time against the flying machine gun and the gun of the Jaegers. Gerry dragged his automatic from his holster and aimed, not with any hope of hitting the German machine, but merely to fire back when fired upon. But he could not twist himself far enough.
“Give me the pistol,” he heard Cynthia say; and, as the German flyer came upon them with his machine gun jetting, he let her hand take the pistol; and while he lay enmeshed, helpless, he heard her firing.
The machine-gun bullets from above splattered past them; the pilot had overflown. The girl had emptied the magazine of Gerry’s pistol and she demanded of him more cartridges. He took his pistol; reloaded it and now, when she reclaimed it, she crouched beside him and shot through a wooden strut and the wires which had been locking his legs in the wreckage. He pulled himself free.
“Now let’s get out of here!” he bid.
“You’re all right?” she asked.
He was testing his legs. “All right,” he assured.
The Jaeger machine gunner had interrupted his fire; and the airplane, which had attacked, was far away at this moment.
“I heard you were about here, Cynthia,” Gerry said. “That’s why— when I had the chance—I came this way.”
She made no reply as she watched the road to the rear upon which the refugees were appearing. A shell burst before them.
“I have to go to them!” Ruth cried.
“They’ll scatter; see; they’re doing it!” Gerry said, as the French ran separately through the fields till the rise of ground guarded them. “But we’d better skip now!”
He had removed his maps from his machine; warning her, he lit a match and ignited the wreckage. The flame, bursting from the gasoline, fed upon the varnished wing fabric, clouding up dense and heavy smoke which drifted with the breeze and screened them as they arose and, crouching, ran. The German machine gunner evidently looked upon the fire as the result of his shots and suspected no flight behind the smoke. The flyer, who had attacked, likewise seemed to see the fire as the result of his bullets. He turned away to other targets.
Gerry got Ruth, unhurt, to the crest of the slope; they slipped over it and for the moment were safe. The car which Ruth had driven stood in the road.
CHAPTER XII
“HOW COULD THIS HAPPEN?”
The French peasants, who had been fired upon and had gained the protection of the slope, gathered about them.
“Beyond, also, the road is open to fire,” Gerry informed them in French; and he directed them to proceed in little groups and by the fields away from the road.
“Monsieur le Lieutenant is wounded,” an old man observed solicitously.
“Barely at all,” Gerry denied; but swayed as he said so.
“Your car must go by the road,” Gerry said to Ruth. “You go with them in the fields; I will take it on for a bit.”
He meant to relieve her for the run over the exposed stretch. He tried to step up to the driver’s seat; but his leg would not bear his weight and he fell backward and would have gone to the ground had Ruth not caught him.
“That’s simply a knee twist from being bent under my ship,” he asserted. “That shrap hardly scratched me,” he referred to the red spot on his side where her fingers were feeling.
“Help me lift Monsieur le Lieutenant,” Ruth bid the old peasant. Gerry tried again to climb alone; but his leg had quite given away. As they lifted, he pulled himself into the seat and took the wheel.
“You need both feet for the pedals,” Ruth reminded him, simply; and he moved over without further protest and let her drive. The car was a covered Ford truck and Gerry, gazing back, saw an old French woman, a child, and two men, who had been injured, lying upon the bedding over the floor. The car was coming to the section of road which the German gunner had registered and Gerry turned about and watched Ruth while she drove.
He had never seen her doing anything like this before; and the sight of her small, white hands, so steady and firm on the wheel, her
little, slender, booted feet upon the pedals sent a thrill tingling through him. He was a little dizzy for a moment and he closed his eyes, clutching to the side of his seat. A shell smashed twenty yards before them; parts of it hit the car. The shock of it startled Gerry up; but the girl beside him was not hit nor frightened. Swiftly she swerved the car to dodge the hole in the road where the gravel was still slipping and settling; the next shell was behind and while they fled now, the shells all were behind and farther and farther back till they ceased.
Ruth halted her car and waited for her charges to gather on the road; all of them appeared; none of them had been hurt. The damage done by the German fire totaled a front wheel much bent and the radiator ruined.
“We’ll have to run hot,” Ruth said. “We can get on, if we go slowly.”
Gerry attempted to get down to walk; but his twisted left knee would not bear him at all. His idea had been to return at once, somehow, to the battle, as soon as this girl who had come to him was in some sort of safety. He had planned wildly, to attempt to join the English fighting to the south of Mirevaux. He couldn’t do that now; but, with strength enough in his leg to move a rudder bar, he could fly and fight again as soon as he could procure another “ship.” The only way he could reach the rear and another airplane was to continue with these refugees and with this girl.
It was strange that when he had been fighting and had been far from her, he had felt more strongly about her than he did now—more about her as a girl, that was, in relation to him as a man. He was close beside her with her body swaying against his when the car careened in the pits and ruts of the road. He kept observing her—the play of color in her smooth skin in the flush of her excitement, the steady, blue eyes alert upon the road, her full, red little lips pressing tight together after speaking with him and drawing tiny lines of strain at the corners of her mouth. He noticed pretty things about her which he had not before—the trimness of her ankles even under her heavy boots, the ease with which that slender, well-formed little body exerted its strength, the way her hair at her temples went into ringlets when effort and anxiety moistened her forehead. But he
noticed these as though to remember them later; his thought seemed to store them and save them for feeling at another time; he was almost aware of going through an experience with her which could affect him, fully, only afterwards. In the same manner that subconsciously he had thought about her when all his conscious thought was absorbed in flying and fighting, now his eyes only observed her; his soul was blent in the battle.
He and she, and the rest, were going back—back, kilometer after kilometer and yet encountering no strong force of English or French in position to hold that land; and he knew that if that depth of front was being abandoned as far away to the right and as far away to the left as he could see, resistance must have broken down over a much greater front. Indeed, Gerry had himself observed from his airplane something of the length of the line where the allies were retreating; but he had not been able, when in the air, and passing in a few seconds over a kilometer, to feel the disaster as now he felt it in the swaying seat of the half-wrecked truck creeping along at the head of a column of refugees. This land which the Germans were again overrunning in a day was the strip which the English had freed the year before only through the long, murderous months of the “blood baths” of the Somme.
“Do you remember an English officer on the Ribot,” Ruth was asking of him, “whom I called ‘1582?’”
“He’s about here?” Gerry inquired.
“No; but several of his sort are—one particularly, a Lieutenant Haddon-Staples; I called him, to myself, ‘1583.’”
“What do you think of his sort now?” Gerry asked, confidently.
Ruth’s eyes filled suddenly so that she had to raise a hand from the driving-wheel to dash away the wetness which blurred the road.
“They’re the most wonderful sportsmen in the world!” Ruth said. “They don’t care about odds against them; or at least they don’t complain. Oh, that’s not the word; complaint is about as far from their attitude as anything you can think of.”
“I know,” Gerry said.
“They don’t even—criticize. They just accept the odds, whatever they are; and go in with all of themselves as though they had a
chance to hold and win and come out alive! They know they haven’t; but you’d never guess it from them; and there’s none of that ‘We who are about to die salute you’ idea in them either. They’re sportsmen and gentlemen!”
“I know how they make you feel,” Gerry said, watching her keenly again; the road thereabouts was bad and she couldn’t even glance around to him. “Rather, you know now how they made me feel, I think.”
She made no reply; so he went on. “If they’d say things out to us; if they had criticized us and damned us and told us we were lying down behind them, it wouldn’t be so rotten hard to see them. But they don’t. They just go in as you say; they feel they’ve a fight on which is their fight and they’re going to fight it whether anyone else thinks it worth while to fight it or not or whether they have any chance for winning.”
Ruth winked swiftly again to clear her eyes; and Gerry, watching her, wondered what particular experience his general praise had called up. He did not ask; but she told him.
“‘1583’ was just that sort of man, Gerry,” she said, using his name for the first time as simply as he had spoken hers when she had crouched behind the shield of his engine with him.
“He’s killed?” Gerry asked.
“I don’t know; but it’s certain—yes, he’s killed,” she replied.
“You—cared for him, Cynthia?”
“He was about here—I mean about Mirevaux—as long as I’ve been. That was only two weeks—‘a fortnight,’ as he’d say in his funny, English way—but now it seems——”
“I know,” Gerry said.
“He was with his battalion which was lying in reserve. He and some of the others didn’t have a lot to do evenings so they’d drop in pretty often at the cottage Mrs. Mayhew and I had where there was one of those little, portable organs with three octaves and we’d play their songs sometimes and ours—like Good King Wenceslaus and Clementine.”
“Did you play?” Gerry interrupted.
“Sometimes; and sometimes he would; and we’d all sing,
In the cabin, in the cañon, Excavating for a mine;
Dwelt a miner, forty-niner—
All the English liked that sort best with Wait for the Wagon, you know.”
“Yes.”
It was a minute or two before she continued; she was speaking of evenings none of them older than two weeks and one of them only the night before last; but they formed part of an experience irrevocable now and of an epoch past.
“They knew pretty well what was going to happen to them—that they would have to be thrown in some day without a chance. But they talked about coming to America after the war—the mining camps of Nevada and California, the Grand Cañon, Niagara Falls, and Mammoth Cave appealed to them, particularly. I asked ‘1583’ once—I knew him best,” Ruth said; and when she repeated the nickname for him it was with the wistful fondness with which only such a name may be said, “if he didn’t want to go back home to England and Suffolkshire after the war He said, ‘I’m eager to stay a bit with the pater and the mater, naturally.’” She was imitating his voice; and Gerry saw that it made her cry; but she went on. “‘But I can’t stay there, you know.’
“I asked, why
“‘My friends,’ he said. ‘I’ve not one now. You fancy you’re attached to a place; but you find, you know, you’ve cared for more than that.’ Then he changed the subject the way the English always do when you come to something they feel. He was with me the evening this battle began; and he knew what was coming. I didn’t see him again till this morning—early this morning,” she repeated as though unable to believe the shortness of the time. “He rode over to warn us; and then, a little later when I was getting my first party of people out of Mirevaux, I passed him with some more men just like him going to the firing. He knew he was going to be killed for he’d told us the Germans had broken through; and we couldn’t hold them. But he wasn’t thinking about that when he saw me. He just watched me as I was working to get my people in order and, as he rode past, he
called out, ‘Good old America!’ That to me—one girl getting peasants out of a village while he and his handful of soldiers were going— there!” Ruth gestured back toward the battle. “Oh, I wanted to be a million men for him—for them! ‘Good old America!’ he said. I saw him, or men whom I think he was with, holding a hill a couple of miles east an hour later; they were one to ten or one to twenty; I don’t know what the odds were against them; but they stayed on top of that hill. I tell you I saw them—stay on top of that hill.”
“I know,” Gerry said. “I’ve seen them stay on top of a hill. I know how it is to want to be, for them, a million men!”
Ruth’s hands on the steering-wheel went bloodless from pressure. “Our million is coming; thank God, it’s coming! And I believe—I must believe that somehow it still is right and best that we couldn’t come before.” She gazed back over the land where the Germans were advancing; and where the English soldiers were “staying.”
“How could this happen, this break-through?” she asked. “It wasn’t just superior numbers; they’ve had that and, at other times, we’ve had superiority before; but no one ever advanced like this.”
“They showed an entirely new attack,” Gerry said. “New infantry formation; new arms—infantry cannon; then there was the mist. And our intelligence people must have fallen down, too, while theirs gave them everything they wanted. We didn’t know at all what they were going to do, but they must have known everything about our strength, or lack of strength, here.”
He saw her hands whiten again with their grasp of the wheel and the little lines deepen under her tight-drawn lips. She had stiffened as though he had accused her; and while he was wondering why, she glanced up at him.
“Then part of this—” her gaze had gone again to the fields being abandoned—“is my fault, Gerry.”
That was all she said; but instantly he thought of her accusation of De Trevenac and what she had told him in the little parlor on the Rue des Saints Pères; and he was so certain that she was thinking of it also that he asked:
“You mean you didn’t tell me all you knew about De Trevenac?”
“No; I told you everything I knew! Oh, I wouldn’t have held back any of that. I mean, I haven’t done all I might; you see, I never imagined anything like this could happen.”
“What might you have done, Cynthia?” he asked. He had said to her that time in the parlor on the Rue des Saints Pères that she had come to do more than mere relief work; but he had not consistently thought of her as engaged in that more daring work against which he had warned her.
“I got so wrapt up in the work at Mirevaux,” she said, avoiding direct answer. “I thought it was all right to let myself just do that for a while.”
“Whereas?” he challenged.
She leaned forward and turned the ignition switch, stopping the motor which had been laboring and grinding grievously. “It must cool off,” she said, leaping down upon the ground. She went about to the back of the truck and Gerry heard her speaking in French to the passengers behind him.
“Grand’mère Bergues,” she said when she returned beside Gerry, “lost for a moment her twig of the tree. I had to find it for her.”
“Her twig of what tree?” Gerry asked.
“I forgot you didn’t know,” and Ruth told him of Grand’mère Bergues’ tree. “When I convinced her at last,” Ruth added, “that the Boche had broken through and were coming again, she had a stroke; but even so she would not let us carry her until I had brought her a twig of the tree—a twig which was green, and budding, and had sap, though last year the Boche called that tree destroyed. That now must be her triumph.”
Ruth restarted the motor and, when they proceeded, Gerry sat without inquiring again of what dangerous, indefinite business this girl was going to do. While he watched her driving, a queer, pulling sensation pulsed in his breast; it associated itself with a vision of a young Englishman, who now undoubtedly was dead, standing behind this girl while she played a little organ with three octaves and they all sang. This was not jealousy, exactly; it was simply recognition of a sort of fellowship which she could share which he would have liked to have discovered himself. It suggested not
something more than he had had with Agnes Ertyle; but something quite different and which he liked. He tried to imagine Agnes playing, and singing Clementine, and Wait for the Wagon; and—he couldn’t. He tried to imagine her crying because someone had called to her, “Good old England”; and he couldn’t. Agnes cried over some things —children who were brought to her and badly wounded boys who died. But Agnes could have told him all that Cynthia had without any emotion at all. Agnes would have told it quite differently, of course.
They were coming in sight of a flying field. “Let me off here, please,” Gerry asked when they were opposite it.
When Ruth stopped the car Gerry called for one of the old Frenchmen to give him a shoulder and he stepped down. “You don’t need much leg muscle to fly,” he assured Ruth when she observed him anxiously. “If I can’t steal a ship over there, at least they’ll take care of me.” He hesitated, looking up at her, unable simply to thank her for what she had done.
“Where are you going?” he asked. During their drive they had discussed various destinations for their party; but could decide upon none. The final halting place must depend upon the military situation, and nothing was more unsettled than that. But Gerry was not referring now to the halting place of the whole party; he knew that during the last minutes she had formed determinations which would take her as soon as possible to her other tasks; and she accepted that in her answer.
“I’m going to Montdidier—unless it seems better to make for Amiens; then to Paris as soon as I can.”
“I see.” He gazed away and up in the air where machines with the tricolor circle of the allies were flying; and hastily he offered Ruth his hand. “Good-bye, Cynthia,” he said.
“Good-bye, Gerry.”
“Cynthia, when you’re in Paris you’ll stay there?”
“I don’t know.”
“If you do, where’ll you be?”
“Milicent’s kept our room in the pension on the Rue des Saints Pères. I’ll be with her again, I think.”
“All right! Look out for yourself!”
“You try to, too!”
She kept the car standing a few seconds longer watching him while, with his arm about the old man’s shoulder, he hobbled toward the flying field. Several minutes later, when she was far down the road, she gazed back, and saw a combat biplane rise from the field with what seemed to be particular impatience, and she imagined that he was piloting that machine. She had passed now from the zone of the broken front, where all the effort was to throw men—any number and any sort of men—across the path of the victorious German advance to the region of retreat, where every sinew and every sense was strained in the attempt to get men, and guns, and supplies out of the area of envelopment by the enemy. And dreadful and appalling as it had been to witness men—too few men and unsupported—moving forward to immolate themselves in hopeless effort to stay that German advance, yet it had not been so terrible to Ruth as this sight and sound of retreat. For the sound—the beat of feet upon the road, the ceaseless tramp of retreating men, the rumble of guns and combat trains going back, then the beat, beat, beat of the retreat—continued into the darkness, when Ruth no longer could see the road from the little house where she rested. All through the night it continued till it seemed to Ruth, not something human, but a cataclysm of nature flowing before a more mighty catastrophe which no one and nothing could stop.
Whenever she awoke she heard it; and through the dreams which harassed the heavy periods of her stupor of exhaustion which served that night for sleep, that beat of the feet throbbed and throbbed.
Ruth reached Montdidier at noon of the next day It was at Montdidier, accordingly, that she first learned the true magnitude of the disaster and first heard openly spoken what had been said only in part before; and that was that the fate of France and of the allied cause depended now upon the Americans. If they could not quickly arrive in great force and if, having arrived, they proved unable to fight on even terms with the Germans, all was lost. France would not yet give up, in any case; England would hold on; but, without America, they were beaten.
And during that day, and through the next, and the next, while Ruth was unable to leave Montdidier, the disaster grew until it was
known that the British Fifth Army, as an organized force, had ceased to exist and the Germans, in this single great stroke, had advanced thirty-five miles and claimed the capture of thirteen hundred guns and ninety thousand men.
On Monday, as the Germans yet advanced and moved on Montdidier, Ruth was in a column of refugees again; she was obliged to abandon her determined task for the duty of the moment offered to her hands. She got to Compiègne and there was delayed. Roye, Noyon, Montdidier all now were taken; and the wounded from that southern flank of the salient which thrust west toward Amiens were coming back upon Compiègne; and no man yet could say that the disaster was halted.
But Foch had come to the command.
Ruth had tried to learn from men who had returned from the region where she had left Gerry Hull, what his fate might have been. She knew that he had been flying and fighting again, for she read in one of the bulletins which was being issued, that he had been cited in the orders of the day for Monday; but she learned nothing at all about him after that until the day after the announcement that all allied armies were to be under the supreme command of General Foch. It was Friday, eight days after that first Thursday morning of mist, and surprise, and catastrophe; and still the Germans fought their way forward; but for two days now the French had arrived, and were present in force from Noyon to Moreuil, and for two days the gap between the British and the French, which the German breakthrough had opened, had been closed.
Gerry upon that day was detailed with a squadron whose airdrome had been moved beyond Ribecourt; he had been flying daily, and had fought an engagement that morning, and after returning from his afternoon reconnaissance over Noyon he had been ordered to rest, as the situation was becoming sufficiently stabilized to end the long strain of his too constant flights. Accordingly, he left late in the afternoon for Compiègne to look for the field hospital where Agnes Ertyle would be at work. The original site of her tents had been far within the zone which the Germans had retaken; and Gerry had heard that she had done wonders during the moving of the wounded.
He found her on duty, as he knew she would be; she was a trifle thinner than before, perhaps; her cool, firm hand clasped his just a bit tensely; her calm, observant eyes were slightly brighter; but she was in complete control of herself, as she always was, quite unconfused—even when two nurses came at the same time for emergency directions—and quite efficient.
After a while she was able to give him a little time alone; and they sat in a tent and talked. Gerry had not seen her or heard from her since the beginning of the battle, and he found her almost overwhelmed with the completeness of the British defeat and the destruction of the Fifth Army. She herself knew and her father, who was dead, had been a close friend of the commanding officers who were held responsible for the disaster; and together with the shock of the defeat, went sympathy for them. They were being removed; and even the English commander-in-chief no longer had supreme command of his own men.
“It’s the greatest thing the allies have yet done—one command,” Gerry said. “We ought to have had it long ago; if we had, the Boche never would have done what they just have. When you had your own army and your own command, and the French had theirs, you each kept your own reserve; and, of course, Ludendorf knew it. Haig expected an attack upon his part of the front, so he had to keep his reserve to himself on his part of the line to be ready for it; the French looked for an attack on their sectors, so they kept their reserves to themselves; so wherever Ludendorf struck with all his reserves, he knew he’d meet only half of ours and that it would take five days—as it did—for the other half to come up. Now one commander-in-chief, like Foch, can stop all that.”
“I can believe it was necessary and, therefore, best,” Lady Agnes said. “Yet I can’t stop being sorry—not merely for our general officers, but for our men, too. Poor chaps who come to me; they’ve fought so finely for England; and now the Boche are boasting they’ve whipped them and beaten England. They everyone of them are so eager to get well, and go back, and have at them again, and rather show the Boche that they’ve not—rather show them that England will have them! Now we’ll not be under our own command; yet we’ll be
fighting just the same for England; the Boche shall find that England will have them!”
“You’ll have them!” Gerry assured. “And far quicker than you could have before.”
Lady Agnes observed him, a little puzzled. “You used to say ‘we’ when you spoke of us,” she said gently.
Gerry flushed. “I was in your army then,” he replied.
“You’re fighting with us now—wonderfully, Gerry.”
“Yes; but technically you see, Agnes, I’m with my own forces.”
He said “my own” with a tone of distinction which surprised himself. His own forces, except for a few comrade pilots, and for those engineers who had grabbed rifles, and got into this battle, and except for those girls—those “awfully good” girls of Picardy—still were only in training in France or holding down quiet sectors in Lorraine. But Gerry had been in one of those sectors which had not been so noted for its tranquillity after “his own” forces had arrived.
However, he was not thinking of those forces just then; he was recalling an American girl who had come to him across open ground in the sunlight and under machine-gun fire. For a moment he visualized her as she stumbled and rolled forward, when he thought she was hit; then he saw her close beside him with the sun on her glorious hair and her eyes all anxious for him. Words of hers came to him when Lady Agnes was speaking again her regret that the English could not have kept their own command.
“Oh, I don’t know how to say it!” that American girl’s words repeated themselves to Gerry; she was in a yellow dress now, with bare arms and neck, and quite warm and flushed with her intentness to explain to him something he could not understand at all. “But at first France was fighting as France and for France against Germany; and England, for England, was doing the same. And America couldn’t do that—I mean fight for America. She couldn’t join with allies who were fighting for themselves, or even for each other. The side of the allies had to become more than that before we could go in; and it is and we’re in!”
Gerry was understanding that better, now. This unification of the command, and the yielding of the British was their greatest earnest
of that change which Cynthia Gail had felt before, and gloried in, and which Agnes Ertyle accepted but yet deplored.
More wounded came streaming back from the battle and Lady Agnes returned to duty immediately. “That Miss Gail, who was on the Ribot with us, was in Compiègne the other day,” Agnes told him when he was saying good-bye. “She’s doing marvels in sorting out refugees, I hear.”
Gerry had been wondering often during the last days about what might have happened to Cynthia; and he had inquired of several people. But he had not thought that Lady Agnes might know.
“She was working at a relief headquarters on Rue Solférino, near the Place de l’Hôtel de Ville.”
Gerry wandered into Compiègne, finding the Rue Solférino, which was the main street of the city, more crowded and congested than ever before. From the throng before the doors, Gerry quickly located the quarters near the Hôtel de Ville where Cynthia Gail had been working and, forcing a way in, he spied a yellow head bent over a little boy and he heard a gentle, sweet voice speaking, in newly learned French, interrogations about where the child last had seen his mother, whether he had aunt or uncle and so on. Gerry went farther in and made himself known; and when the girl looked up and saw him, an older American woman—Mrs. Mayhew—looked up, and she observed not only Gerry but the girl also.
“Hello,” Ruth said. It was a poor word to encompass all she was feeling at that moment, which was, first, joy and relief that he was safe; next, that he had come there to seek her. But the word did, as it many, many times had done before; and he used the same to encompass what he felt. “Have you had anything to eat tonight?” he added after his greeting. He suspected not.
“I’ll have supper later, thanks,” Ruth said.
“You will not,” Mrs. Mayhew put in. “You can come back after supper, if you must; but you go out now. Take her with you, Gerry.”
Which was a command which Gerry obeyed. So they sat together at a little table in a café, much crowded, and very noisy, and where they supped in haste; for there was a great multitude to be served. But they were very light-hearted.
“You’ve heard the great news about our army?” Ruth asked.
“That we’re going to be under the command of General Foch like the English?”
“Better than that,” Ruth said. “General Pershing has offered all our forces to the French to use in any way they wish. He’s offered to break up our brigades, or even our regiments and companies, and let the French and English brigade our regiments with them, or take our men as individuals into their ranks, or use us any way they want, which will help to win. They’re not to think about us—our pride—at all. They’re just to take us—in any way to help.”
“No,” said Gerry. “I hadn’t heard that.”
“It’s just announced,” Ruth told him. “I’d just heard. He did it under the instructions and with the approval of our government. I think—I think it’s the finest, most unselfish offer a nation ever made! All we have in any way that’s best for the cause!”
Gerry sat back while hot rills of prickling blood tingled to his temples. “I think so, too, Cynthia,” he said. And again that evening words of hers, spoken long ago, seized him. “Oh, I don’t know how or when it will appear; but I know that before long you will be prouder to be an American than you ever dreamed you could be!”
Part of that pride was coming to him, then, incredible as it would have seemed to him even a few days ago, when in the midst of disaster unparalleled and due to the tardiness of his country. For, though his country had not come in till so late, now it was offering itself in a spirit unknown in national relations before.
When they had finished their supper, he brought her back to her work and himself returned to his airdrome. The next day Ruth found a chance to journey to Paris.
For information—accurate, dependable word of German intentions and German preparations for the next attack—was the paramount essential now. This first assault at last was stopped; but only after tremendous catastrophe; and the Germans still possessed superiority in physical strength as great as before. And they owned, even more than before, confidence in themselves, while the allies’ at least had been shaken. The Germans kept also, undoubtedly, the same powers of secrecy which had enabled them to launch their
tremendous onslaught as a surprise to the allies, while they themselves accurately had reckoned the allied strength and dispositions.
Ruth did not hope, by herself, to change all that. The wild dreams of the girl who had taken up the bold enterprise offered her in Chicago, had become tempered by experience, which let her know the limits within which one person might work in this war; but the probability that she would be unable to do greatly only increased her will to do whatever she could.
Thus she returned to Paris to endeavor to encounter again the enemy agents who would send her through Switzerland into Germany. As she knew nothing of them, she must depend upon their seeking her; so she went at once to her old room in the pension upon the Rue des Saints Pères. Arriving late in the afternoon, she found Milicent home from work—a Milicent who put arms about her and cried over her in relief that she was safe. Then Milicent brought her a cablegram.
“This came while you were gone, dear. I opened it and tried to forward it to you.”
Ruth went white and her heart halted with fear. Had something happened at home—to her mother or to her sisters?
“What is it?”
“Your brother’s badly wounded. He’s here in a hospital, Cynthia!”
“My brother!” Ruth cried. It had come to her as Cynthia Gail, of course. She had thought, when nearing the pension, that probably she would find an accumulation of mail to which, as Cynthia, she must reply. But she had been Cynthia so long now that she had almost ceased to fear an emergency. Her brother, of course, was Charles Gail, who had quarreled with his father and of whom nothing had been heard for four years.
Ruth took the message and learned that Charles had been with the Canadians since the start of the war; he had enlisted under an assumed name; but when wounded and brought to Paris, he had given his real name and asked that his parents be informed. The information had reached them; so his father had cabled Cynthia to try to see Charles before he died.
“I told Lieutenant Byrne about it,” Milicent said to Ruth.
“Lieutenant Byrne?”
“Why, yes; wasn’t that right? He called here for you last week; and several times since. He said he was engaged to you; why—isn’t he?”
“Yes, he was. That’s all right,” Ruth said.
“So he’s been about to see your brother.”
“How is he? Charles, I mean, of course.”
“He was still living yesterday.”
“Lieutenant Byrne is still here?”
“As far as I know, he is.”
CHAPTER XIII BYRNE ARRIVES
Ruth turned, without asking more, and went into the room which had been hers, and shut herself in alone. She dared not inquire anything further, or permit anything more to be asked of her; she dared not let Milicent see her until she had time to think.
Milicent and she long ago had given to one another those intimate confidences about their personal affairs which girls, who share the same rooms, usually exchange; but Ruth’s confidences, of course, had detailed the family situation of Cynthia Gail. Accordingly, Ruth knew that Milicent had believed that the boy, whose picture was the third in the portfolio of Cynthia’s family, which Ruth always had kept upon the dresser, was Ruth’s brother. Milicent would believe, therefore, that it was this sudden discovery of her brother dying in a Paris hospital which had shocked Ruth into need for being alone just now.
Indeed, feeling for that boy, whose picture she had carried for so long, and about whom she had written so many times to his parents, and who was mentioned in some loving manner in almost every one of those letters which Ruth had received from Decatur, had its part in the tumult of sensations oversweeping her. But dominant in that tumult was the knowledge that his discovery—and, even more certainly, the arrival of George Byrne—meant extinction of Ruth as Cynthia Gail; meant annihilation of her projects and her plans; meant, perhaps, destruction of her even as Ruth Alden.
Ruth had not ceased to realize, during the tremendous events of these last weeks, that at any moment someone might appear to betray her; and she had kept some calculation of the probable consequence. When she had first embraced this wild enterprise, which fate had seemed to proffer, she had entered upon considerable risks; if caught, she would have the difficult burden of proof, when she was taking the enemy’s money and using a
passport supplied by the enemy and following—outwardly, at least— the enemy’s instructions, that she was not actually acting for the enemy. But if she had been betrayed during the first days, it would have been possible to show how the true Cynthia Gail met her death and to show that she—Ruth Alden—could have had no hand in that. But now more than two months had passed since that day in Chicago when Ruth Alden took on her present identity—more than two months since the body of Cynthia Gail, still unrecognized, must have been cremated or laid away in some nameless grave. Therefore, the former possibility no longer existed.
Horror at her position, if she suddenly faced one of Cynthia Gail’s family, sometimes startled Ruth up wide-awake in bed at night. She had not been able to think what to do in such case as that; her mind had simply balked before it; and every added week with its letters subscribed by those forged “Thias” to Cynthia’s father, and those intimate endearments to Cynthia’s mother, and those letters about love to George Byrne—well, every day had made it more and more impossible to prepare for the sometime inevitable confession.
For confession to Cynthia’s family must come if Ruth lived; but only—she prayed—after the war and after she had done such service that Cynthia’s people could at least partially understand why she had tricked them. The best end of all, perhaps—and perhaps the most probable—was that Ruth should be killed; she would die, then, as Cynthia, and no one would challenge the dead. That was how Ruth dismissed the matter when the terror within clamored for answer. But she could not so dismiss it now.
Impulse seized her to flee and to hide. But, in the France of the war, she could not easily do that; nor could she slip off from Cynthia’s identity and name without complete disaster. Anywhere she went—even if she desired to take lodgings in a different zone in Paris, or indeed if she was to dwell elsewhere in the same zone— she must present Cynthia’s passport and continue as Cynthia. And other, and more conclusive reasons, controlled her.
Her sole justification for having become Cynthia Gail was her belief that she could go into Germany by aid of the German agents who would know her as Cynthia Gail. They could find her only if she went about Cynthia Gail’s work and lived at the lodgings here.
