Iceb e r g s a nd G lac i e r s
Hi ghlights From Issue 15 (August 2009) Bergterranova2. Photo courtesy of Mike Usher, U.S. Antarctic Program, National Science Foundation.
Table of Contents
Icebergs and Glaciers, Issue 15 (Aug. 2009) Science Content Knowledge
Glaciers: Earthâ€™s Rivers of Ice
By Jessica Fries-Gaither
Literacy Content Knowledge
Visualizing to Understand Content Area Text
By Jessica Fries-Gaither
By Stephen Whitt
Across the Curriculum: Content Knowledge
All About Icebergs
By Jessica Fries-Gaither and Alison Schirmer Lockman
Common Misconceptions About Icebergs and Glaciers
By Jessica Fries-Gaither
Across the Curriculum: Lessons and Activities
Using Icebergs to Teach Buoyancy and Density
By Jessica Fries-Gaither
Science & Literacy: Lessons and Activities
Hands-on Lessons and Activities about Glaciers
By Jessica Fries-Gaither
Off the Bookshelf
Icebergs and Glaciers: Virtual Bookshelf
By Julie Moran
Science Content Knowledge Glaciers: Earthâ€™s Rivers of Ice By Jessica Fries-Gaither Did you know that 10 percent of the world's total land area is covered by glaciers? Or that glaciers store 75 percent of the world's freshwater? Glaciers range in size from football fields to over a hundred kilometers long, occur on every continent and in 47 countries, and are harbingers of our changing climate. Read on to learn more about these massive "rivers of ice." WHAT IS A GLACIER? Simply stated, a glacier is a large, slow-moving mass of ice. While there are many types of glaciers, they can be divided into two categories: alpine and continental. Alpine glaciers are found in a mountainous region and flow down valleys. Continental glaciers are domeshaped glaciers that flow away from a central region and are largely unaffected by the land's topography. The Greenland and Antarctic ice sheets are examples of continental glaciers. Smaller masses of ice, called ice caps, are also considered continental glaciers.
Alpine glaciers are further classified by their shape as well as the surface they flow onto. Alpine glaciers include: piedmont, tidewater, and hanging glaciers (see right column). HOW DO GLACIERS FORM?
Alpine Glaciers Piedmont glaciers occur when a glacier extends down a steep valley onto a relatively flat plain. The defining characteristic of a piedmont glacier is the bulblike lobe that forms at the terminus (end) of the glacier.
Tidewater glaciers occur when a Glacial ice forms from compacted snow. Illustration courtesy of Luis Maria Benitez, Wikimedia Commons.
Glaciers form in areas where cold temperatures allow snow to build up over many years (such as the polar and high-altitude alpine regions). The snow is compressed and compacted, becomes granular, and eventually becomes denser snow called firn. Over time, the weight and pressure of the accumulating snow causes the firn to become a thickened mass of ice.
glacier flows down a valley and reaches out into the sea. Tidewater glaciers calve numerous icebergs.
Hanging glaciers are also known as ice aprons. They cling to steep mountainsides and are wider than they are long. This type of glacier is common in
Dense glacial ice looks somewhat blue because the air spaces in the layers have been compressed. Less compressed (and less dense) ice appears white.
the Alps. Top: Piedmont Glacier. Photo courtesy of geefour907, Flickr; Middle: Tidewater Glacier. Photo courtesy of Alan Vernon, Flickr; Bottom: Hanging Glacier. Photo courtesy of Alaskan Dude, Flickr.
Science Content Knowledge
In 1986, the Hubbard Glacier in Alaska surged at the rate of 10 meters per day for several months!
surged at the rate of 10 meters per day for several months!
GLACIERS ON THE MOVE The pressure of a glacier's own weight and the force of gravity cause the glacier to move (or flow) outward and downward. Alpine glaciers flow down valleys, and continental glaciers flow outward in all directions from a central point.
Glaciers move by two mechanisms: internal deformation and sliding. Internal deformation occurs when the enormous mass of a glacier causes it to spread out due to gravity. Sliding occurs when the glacier slides on a thin layer of water at the base (also known as subglacial water). This water comes from melting due to the intense pressure at the base of the glacier, or from water that has seeped through cracks in the glacier. Glaciers typically move slowly, with changes only noticeable over months or years. However, glaciers may surge - move forward several meters per day for weeks or months. In 1986, the Hubbard Glacier in Alaska 4
Friction at the base of a glacier causes the underside to move more slowly than the top. Rapid movement of a glacier causes stresses to build up in the ice, forming cracks, called crevasses, at the glacier's surface. Crevasses may be small or quite large, and they pose a real hazard to anyone moving about on a glacier. GLACIAL EROSION Glaciers primarily erode through plucking and abrasion. Plucking occurs as a glacier flows over bedrock, softening and lifting blocks of rock that are brought into the ice. The intense pressure at the base of the glacier causes some of the ice to melt, forming a thin layer of subglacial water. This water flows into cracks in the bedrock. As the water refreezes, the ice acts as a lever loosening the rock by lifting it. The fractured rock is thus incorporated into the glacier's load and is carried along as the glacier slowly moves.
Ice Flow Glacier abrasion
Abrasion happens when the glacier's ice and rock fragments act as sandpaper, crushing the rock into finely grained rock flour and smoothing the rock below. Meltwater streams of many glaciers are grayish in color due to high amounts of rock flour. Glacial erosion is evident through U-shaped valleys with flat bottoms. Mountain valleys typically have a sharp V-shape, and the glaciers deepen, widen, and smooth them. Fjords are also formed in this manner. Other features created by glaciers include arêtes, cirques, and horns. Arêtes are thin ridges of rock formed by glacial erosion on both sides. Cirques are U- or bowl-shaped basins formed in the sides of mountains. A glacial horn has near vertical faces on all sides. RETREATING GLACIERS How does a glacier retreat? While many people misinterpret the notion of retreat to mean that the glacier is moving backward, this is not physically possible due to the force of gravity. Instead, glacial retreat actually involves the balance of ice accumulation and ice loss. A glacier accumulates mass as snow builds up and persists Glacial plucking and abrasion. Illustration of Luis Maria Benitez, Wikimedia Commons.
Science Content Knowledge could be living with little drinking water. This is also true of alpine glaciers in tropical areas, like the Andes. These glaciers are at especially great risk because they tend to be smaller and because the tropics are more sensitive to climate change.
A glacial moraine in Kyrgyzstan. Photo courtesy of Martin Talbot, Flickr.
through summer melt seasons, eventually compacting and forming new ice. However, a glacier also loses mass through melting, sublimation, and calving. As long as accumulation is greater than loss, the health of the glacier is maintained and the glacier will advance. However, if snowfall decreases, temperatures rise, or ice loss increases to the extent that the loss of the ice is continually greater than its accumulation, the glacier will retreat. As a glacier retreats, it leaves behind large piles of rock, gravel, and even boulders. These sediment deposits are called moraines. Moraines may form at the foot (terminal moraine) or sides (lateral moraine) of the glacier or in the middle of two
merging glaciers (medial moraine). GLACIERS AND PEOPLE Alpine glaciers often feed rivers used for their freshwater. Glaciers in the Himalayas contain the largest store of water outside of the Greenland and Antarctic ice caps, and feed seven major Asian rivers: the Ganges, Indus, Brahmaputra, Mekong, Thanlwin, Yangtze, and Yellow Rivers. As the temperatures rise and glaciers retreat, there is growing concern about water shortages among the millions of people who depend on glacially fed rivers for their water supply. If these Himalayan glaciers continue to retreat at their current pace, the 40 percent of the world's population living in these areas
GLACIERS AND CLIMATE CHANGE Glaciers have formed, advanced, and retreated many times throughout earth's history as global temperatures rose and fell. Today, climate change is causing rapid decline of glaciers and ice sheets across the globe. The study of glaciers can help monitor climate change, but because of their size, they can be difficult to study. Scientists use techniques such as remote sensing, photogrammetry, and even "glacier cams" to measure the mass balance of glaciers and ice sheets. This helps them understand how rapidly the glaciers and ice sheets are changing. Some scientists are using data from ice and sediment cores to reconstruct past climates. By understanding how glaciers and ice sheets formed and changed in the past, scientists hope to better understand and predict how they will respond in today's changing climate. 5
Science Content Knowledge Yet other scientists are trying to understand the behavior of glaciers. What causes them to surge? Calve? In Greenland, scientists have observed large ponds of meltwater suddenly drain away. They wonder where this water goes and how it might affect the glacier's movement.
Water Science Basics: Glaciers and Icecaps http://ga.water.usgs.gov/edu/ earthglacier.html Part of the U.S. Geological Survey's Water Science for Schools web site, this page provides an overview of glaciers and ice sheets.
Better understanding of glacier dynamics, past behavior, and current changes will help scientists model and predict the changes to come.
Center for the Remote Sensing of Ice Sheets (CReSIS) https://www.cresis.ku.edu/ Based at the University of Kansas, CReSIS is comprised of six partner universities. Researchers and graduate students use remote sensing to monitor and understand changes in the Greenland and Antarctic ice sheets.
LINKS All About Glaciers http://nsidc.org/glaciers/ Learn how glaciers form, move, and shape the landscape.
Better understanding of glacier dynamics, past behavior, and current changes will help scientists model and predict the changes to come.
Above: Greenland Ice Sheet. Photo courtesy of chrissy575, Flickr. Right: An Iceberg of Two Faces. Photo courtesy of SF Brit, Flickr.
NATIONAL SCIENCE EDUCATION STANDARDS: SCIENCE CONTENT STANDARDS The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. The following excerpt was taken from Chapter 6, http:// books.nap.edu/openbook.php? record_id=4962&page=103. Teaching about glaciers can meet the Earth and Space Science content standard for grades K-4 and 5-8: K-4 Earth and Space Science • Properties of Earth Materials 5-8 Earth and Space Science • Structure of the Earth System
Literacy Content Knowledge Visualizing to Understand Content Area Text
By Jessica Fries-Gaither Reading in the content areas is often difficult for students. The bulk of traditional reading instruction (especially in the primary grades) is based on fiction texts. This often leaves students unprepared for the volume of nonfiction, or informational text, that is used in the upper elementary, middle, and high school years. In addition, informational text comprises the majority of passages included on standardized tests as well as the type of reading that most students will do outside the classroom. Students need explicit instruction in comprehension strategies appropriate for informational text and opportunities for repeated practice. In past months, we've focused on comprehension strategies such as making inferences, determining importance, note taking, and questioning. This month's comprehension strategy, visualizing, promotes deeper comprehension of both informational and fictional text.
57449720. Photo courtesy of Stockbyte.
WHAT IS VISUALIZING? According to Into the Book, a reading strategies web site, visualizing can be defined as: “Readers [creating] images in their minds that reflect or represent the ideas in the text. These images may include any of the five senses and serve to enhance understanding of the text.” Research shows that proficient readers create mental images spontaneously and purposefully during and after reading. These images help readers recall details and draw conclusions. Visualizing also helps students create nonlinguistic representations, or understandings, of concepts that do not involve words. Nonlinguistic representations are a powerful tool for learning and one of nine research-based
Research shows that proficient readers create mental images spontaneously and purposefully during and after reading.
strategies discussed in Classroom Instruction That Works, a 2001 book by Robert Marzano, Debra Pickering, and Jane Pollock.
HOW CAN TEACHERS USE THE STRATEGY WITH NONFICTION? Visualizing can be used before, during, and after reading. Into the Book provides suggestions for using images and visual imagery with nonfiction text. As with any comprehension strategy, be sure to model the thinking processes involved! It is also important to remind students that the effectiveness of the strategy does not depend on their artistic ability. As long as the images are meaningful to the student, they will enhance comprehension of the text in question.
Literacy Content Knowledge Before Reading • Have students preview and sort images from a text. • "Picture walk" through a text and make predictions about the content, based on the images. • Use Guided Imagery, http:// reading.ecb.org/downloads/ vis_lp_GuidedImagery.pdf, to prepare students for reading. • Have students draw pictures to document prior knowledge. Compare these pictures in
RESOURCES FOR VISUALIZING We've created a template that can be used to help students visualize this month's Feature Story, "Ice Sculptures." The template is based on a researchbased activity called Gallery Images, http://reading.ecb.org/ downloads/ vis_lp_GalleryImages.pdf.
small groups, and use them as the basis for a whole-class discussion. During Reading • Ask students to explain how individual images support the main idea of the passage or book. • Discuss the relationships between the images within a text. • Have students sketch while listening to a read-aloud.
After Reading • Have students make a drawing based on what they read. Compare this drawing to their prior knowledge. • Complete Venn diagrams, charts, or grids based on the text.
Visualizing Glaciers http://onramp.nsdl.org/eserv/ onramp:17405/ Visualizing_Glaciers.pdf This template can be printed and used in conjunction with the Feature Story, "Ice Sculptures" (see page 9). As they read, students create images to represent the content and write a caption to accompany each image.
Into the Book http://reading.ecb.org/ index.html Into the Book is a reading comprehension resource for K-4 students and teachers. It focuses on these researchbased strategies: Using Prior Knowledge, Making Connections, Questioning, Visualizing, Inferring, Summarizing and Synthesizing.
Literacy Set http://rs1.contentclips.com/ipy/ fwd/ipy_0908_set_lit_6031.html Everything you need to teach the strategy of visualizing: a content knowledge article, template, and illustrated and electronic book copies of "Ice Sculptures" at all three grade bands.
Visualizing http://www.ohiorc.org/adlit/ strategy/strategy_each.aspx? id=6 This article, available from the Ohio Resource Center's AdLIT Reading Strategies web page, discusses the process of visualizing as well as what teachers can do to support students as they practice the strategy.
A glacier on Greenland. Photo courtesy of Jolanta DudzinskaPettersen, Wikimedia Commons.
Compare these pictures in small groups, and use them as the basis for a whole-class discussion.
Feature Story: Ice Sculptures Ice Sculptures By Stephen Whitt
Stories for Students (and Teachers)! This nonfiction article is written for use with upperelementary students (grades 4-5). Modified versions are available for students in grades K-1 and grades 2-3, or any student needing a simplified version. As always, consider the reading level and needs of your students when selecting a version for classroom use. At each grade level, the article is available in three forms. Printable pdf files allow you to print this story in either text or a foldable book format. A partnership with Content Clips has allowed us to create electronic versions of the articles. Your students can read along as they listen to the text - a wonderful way to support struggling readers! Reading strategy templates and related activities provide suggestions for integrating this story with your science and literacy instruction.
In the Kalahari Desert of South Africa are some odd-looking rocks. The rocks are flat and polished, as if something very large and heavy has scraped across their surface. Halfway across the world, in the southwest corner of Lake Erie, is Kelleys Island. The bedrock there is grooved. It looks as if something large and heavy has moved across the rock, gouging out these deep lines. What caused these strange things? The flat, polished rocks of South Africa and the grooved rocks of Kelleys Island were left behind by giant moving walls of ice called glaciers. Glaciers are made of ice. Ice is a solid. But glaciers are so large and heavy that they actually move like a liquid. You can think of glaciers as slow-moving rivers of ice. Today glaciers can be found on very high mountains. Snow falling on high mountain slopes doesn't melt. Instead the snow turns to ice and adds its own weight to
the weight of ice already there. When the ice is heavy enough, the glacier begins to move down the mountain, spreading into the foothills and valleys below. As it moves, the glacier scrapes and shapes the mountain's sides. Like mountaintops, polar regions stay cold all year long. Glaciers grow there too. They press and grind the land below as they move. When a glacier reaches a coastline, pieces of ice can break off and form icebergs. Today glaciers are found in only the world's coldest places. But during ice ages, glaciers and ice sheets covered the land over much of Earth. Three hundred million years ago, the Kalahari Desert was covered by glaciers. That ice slowly moved. It scraped across the rock, leaving the flat, smooth rocks behind. Starting around three million years ago, an ice sheet covered much of the midwestern United States. This ice sheet advanced and retreated many times. It retreated for the last time around fourteen thousand years ago. This ice sheet is responsible for the glacial grooves of Kelleys Island. As the glacier moved, it picked up heavy boulders and pushed
Feature Story: Ice Sculptures
Fjord. Photo courtesy of Finnrind, Wikimedia Commons.
them along. These boulders, some made of hard rock, scraped at the softer limestone of Kelleys Island, forming long channels. These channels are the glacial grooves of today. They are clear evidence of the wall of ice that once moved across the land. Ice has shaped the world in surprising ways. The rugged coastline of Norway was once covered in ice. Today, fjords line the coast. Fjords are fingers of water that stretch inland along ushaped valleys. Moving ice carved those valleys. The mountains of Europe and the Great Lakes of North America were also sculpted by ice. Glaciers formed giant lakes where none had been before and produced rich soil for growing crops. Even though the glaciers have retreated, we can see their sculptures all around us. 10
Glacier. Photo courtesy of Wikimedia Commons.
GLOSSARY fjord - a deep valley filled with water glacier - a large mass of ice that slowly moves ice ages - times in Earth's history when the world was extremely cold icebergs - large pieces of ice that float in the sea ice sheet - a mass of ice that covers more than 19,000 square miles of land READING STRATEGY TEMPLATES The article provides an opportunity for students to practice the comprehension strategy of visualization. The following template can be used in conjunction with "Ice Sculptures." For more information on this strategy, please see "Visualizing to
Iceberg. Photo courtesy of ramonbaile, Flickr.
Understand Content Area Text" (on page 7). Visualizing Glaciers http://onramp.nsdl.org/eserv/ onramp:17405/ Visualizing_Glaciers.pdf This template can be printed and used in conjunction with the Feature Story, "Ice Sculptures." As they read, students create images to represent the content and write a caption to accompany each image. Literacy Set http://rs1.contentclips.com/ipy/ fwd/ipy_0908_set_lit_6031.html Everything you need to teach the strategy of visualizing: a content knowledge article, template, and illustrated and electronic book copies of "Ice Sculptures" at all three grade bands.
Across the Curriculum All About Icebergs By Jessica Fries-Gaither and Alison Schirmer Lockman Icebergs, like penguins and polar bears, are an iconic symbol of the polar regions. You may have seen spectacular images of towering, sculpted white ice or even pictures of blue or striped icebergs. How are they formed? What causes differences in color? How do these massive chunks of ice float? Read on to learn about all things iceberg! ICEBERGS 101 Icebergs are found in the Arctic, North Atlantic, and Southern Oceans. Icebergs float in salt water because they are formed by calving, or splitting, glaciers and are thus made of fresh water. The size of icebergs varies widely. Small bergs (a little smaller than a car) are known as
Blue Icebergs. Photo courtesy of stock.xchng.
"growlers," while slightly larger bergs (about the size of a house) are called"bergy bits." Larger bergs are classified as small, medium, large, and very large. And very large they can be. The tallest known iceberg in the North Atlantic was 550 feet (168 m) above sea level. Since the bulk of an iceberg is below the water, the entire berg was estimated to be as tall as a 55story building! Iceberg B-15, which calved from the Ross Ice Shelf of Antarctica in 2000, was half a mile thick and covered an area of about 4,500 square miles (about the size of Connecticut). B-15 subsequently broke into smaller pieces, named B-15A, B-15B, and so on. Why did this massive berg break apart? Seismic recordings showed that an Arctic storm six days prior to the event was to blame. The storm created ocean swells that traveled over 8,000 miles and caused B-15 to crash repeatedly against the coast. Icebergs are also classified by their shape. Tabular icebergs have steep sides and a flat top like a plateau, while nontabular icebergs include irregular shapes such as rounded tops, spires, sloping sides, and blocks. Wind and water erode icebergs into
amazing sculptural shapes. Most icebergs are white in color, but some may appear blue or even green. Ice is full of tiny air bubbles that scatter all color wavelengths the same amount, giving the ice a white appearance. If the ice is compressed, the bubbles are squeezed out and the blue light is scattered much more than other colors - making the ice appear blue. Algae often grow on the underside of sea ice and icebergs, producing green stripes that are only revealed when the ice rolls over and exposes the previously underwater sections. THE TIP OF THE ICEBERG You have probably heard the statistic that approximately 90 percent of an iceberg is found under water. That's an amazing statistic to consider given the massive size of some icebergs, but the very fact that ice floats is pretty remarkable. To understand why ice floats, it is necessary to understand the concept of density. Density is calculated by dividing an object's mass (amount of matter) by its volume (the space it occupies), or D=M/V. Density essentially describes how tightly packed a substance's atoms are. Substances with a high density have tightly packed atoms, while the atoms in a low11
Across the Curriculum density substance are more spread out. Density is a defining property of a substance, and it is constant no matter how much of the substance there is. For example, pure gold always has a density of 19.3 g/mL (grams per milliliter). Pure liquid water's density is 1.0 g/mL, and a standard by which to compare other substances. When water freezes, the water molecules spread out to align in a definite crystalline structure. You've observed this if you've ever noticed the bump on an ice cube or had a can of soda explode in the freezer. While most other substances contract, water expands as it becomes a solid. Because water expands as it freezes, ice takes up more space (has a greater volume) than the liquid water does. But the amount of matter hasn't changed - it is just spread out over a larger space. This means
Iceberg. Photo courtesy of ramonbaile, Flickr.
that the density of ice (0.92 g/ mL) is less than that of liquid water (1.0 g/mL). And because ice's density is lower than that of water, ice floats in water. What about the density of salt water? Because of the dissolved sediments and minerals, sea water is slightly denser than pure water. Its density is approximately 1.03 g/mL. That means that ice (like icebergs) also floats in sea water. In fact, fresh water from melting icebergs will form a layer on top of the denser sea water. Density also explains why most of an iceberg is found beneath the ocean's surface. Because the densities of ice and sea water are so close in value, the ice floats "low" in the water. Remember that the density of ice is 0.92 g/mL, and the density of water is 1.0 g/mL (1.03 for salt water). This means that ice has nine-tenths, or 90 percent of water's density - and so 90
percent of the iceberg is below the water's surface. In contrast, a piece of wood with a density of 0.5 g/mL (half that of water) would float with half of its volume below the surface of the water. A cork with a density of 0.2 g/mL (20 percent that of water) would float with 20 percent of its volume below the surface, and so on. Of course, there are some small variations that affect the exact percentage of the iceberg below water. Icebergs may contain sediments, dust, and other particles picked up by the glacier before calving. They also may have algae growth in and on their submerged surface. These icebergs are not a pure substance, and thus their density is no longer 0.92 g/mL. The temperature and salinity of the water in which an iceberg is located may also vary, meaning that the sea water's density may not be exactly 1.03 g/L. While
Across the Curriculum
Blue Icebergs. Photo courtesy of stock.xchng.
these variations are common, they do not change the densities much - and so 90 percent is a good estimate for the submerged part of an iceberg! LIFE CYCLES AND ECOSYSTEMS? Although they aren't living, icebergs do have a life cycle. They begin as part of a glacier, building for tens of thousands of years and slowly moving toward the ocean. Once an iceberg calves, it typically lasts for three to six years - shorter if it floats into warmer water. Waves wear away at the iceberg and crash it into other icebergs or land. Thawing and melting create crevasses (cracks) that may lead to further calving. Some icebergs simply melt away, while others collapse more violently. Some icebergs never move into warmer waters and may last 50 years or more.
Icebergs may appear sterile and lifeless, but that's not the case. Ice algae may grow inbetween ice crystals or on the underside of a berg, playing an important role in primary production and in the marine ecosystems. Small fish avoid predators by hiding in ice holes, while invertebrates come to feed on nearby krill. Seabirds may nest on icebergs as well. Extremely large icebergs, such as B-15 and the more recent C-19, can negatively impact marine ecosystems. Large bergs can reduce the amount of sunlight hitting the water, thus decreasing the production of the phytoplankton that forms the base of the marine food web. They also block the paths that penguins use to reach open water to find food. Icebergs near the coast of Antarctica scour, scrape, and gouge the seafloor. Increased calving as a result of shrinking winter sea ice will create more disturbances on the seabed, where the majority (80 percent) of all Antarctic life occurs. While some disturbances create space for a high diversity of organisms,
scientists believe that an increase in iceberg action may actually decrease biodiversity. DANGER! The well-known story of the RMS Titanic, which illustrates the hazards of icebergs, led to the formation of the International Ice Patrol. The Ice Patrol (administered by the U.S. Coast Guard) keeps a close watch over the area off the coast of Newfoundland, known as Iceberg Alley because of the high number of icebergs found in the waters. The Ice Patrol collects data from a variety of sources: aircraft flights, radar, and ice sightings from ships. It uses computer modeling and current information to predict the path of icebergs and warn ships via radio and the Internet. While these precautions have reduced
NSF helicopter support in Antarctica. Photo courtesy of Carol Landis, Byrd Polar Research Center.
Across the Curriculum appropriate for upper elementary students as well as teachers. How Icebergs Work http:// science.howstuffworks.com/ iceberg.htm A six-part article providing an overview of iceberg basics, life cycle, statistics, ecology, and danger. Icebreakeredge. Photo courtesy of Josh Landis, U.S. Antarctic Program, National Science Foundation
the number of incidents with icebergs, the risk still remains. The Antarctic Circumpolar Current tends to trap icebergs within the Southern Ocean, although some occasionally escape and enter shipping lanes in the southern Atlantic, Indian, and Pacific Oceans. Icebergs and sea ice do present a problem for research vessels and cruise ships within the Southern Ocean, however. LINKS Icebergs http://oceanworld.tamu.edu/ students/iceberg/ This site provides basic information and interesting facts about icebergs, shapes, sizes, and colors, the journey of an Arctic iceberg, dangers, and possible uses. The site may be
Quick Facts: Icebergs http://nsidc.org/quickfacts/ icebergs.html This page from the National Snow and Ice Data Center provides basic information on icebergs as well as links to the International Ice Patrol, U.S. National Ice Center, and other useful resources. Density of Ice http://www.elmhurst.edu/ ~chm/vchembook/ 122Adensityice.html This page explains the concept of density, provides an explanation of why ice is less dense than water, and why ice floats. Icebergs are Hotspots for Life http://scienceblogs.com/ notrocketscience/2009/05/ icebergs_are_hotspots_for_life. php This blog post discusses the ecosystem found around and on the underside of icebergs.
NATIONAL SCIENCE EDUCATION STANDARDS: SCIENCE CONTENT STANDARDS The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. The following excerpt was taken from Chapter 6, http:// books.nap.edu/openbook.php? record_id=4962&page=103. Teaching about icebergs can meet the Physical Science content standard for grades K-4 and 5-8: K-4 Physical Science Properties of Objects and Materials â€˘ Materials can exist in different states - solid, liquid, and gas. Some common materials, such as water, can be changed from one state to another by heating or cooling. 5-8 Physical Science Properties of Objects and Materials â€˘ A substance has characteristic properties, such as density, a boiling point, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.
Misconceptions Common Misconceptions about Icebergs and Glaciers By Jessica Fries-Gaither An Antarctic iceberg's massive size is amazing, as is an Arctic glacier's power to shape the landscape. Yet misconceptions about icebergs and glaciers exist among students of all ages (and adults). Many of these misconceptions deal with density and buoyancy; others concern the formation of glaciers
and icebergs or their effects on earth's land and water. Effective instruction begins by considering student misconceptions and planning activities accordingly. In this article, we've highlighted some common misconceptions about icebergs and glaciers and the underlying concepts of density and buoyancy. Rather than provide an exhaustive list of all possible student ideas, we hope to give insight into ones that might be held by your elementary students. We've also provided tools for formative assessment and resources for teaching correct scientific concepts.
In this article, we've highlighted some common misconceptions about icebergs and glaciers and the underlying concepts of density and buoyancy.
A NOTE ABOUT DENSITY AND BYOYANCY Density and buoyancy are important concepts to consider when teaching about icebergs and glaciers. Answering common questions from
MISCONCEPTIONS: ICEBERGS S t u d e n t s m ay thi nk ...
Inste ad o f th in kin g. ..
Icebergs are made of salt water.
Icebergs float in salt water, but they are formed from freshwater glacial ice.
Melting icebergs will cause sea level to rise.
Icebergs are already floating in the ocean, so melting will not raise sea level. Melting of land-based ice (such as glaciers) will raise sea level.
MISCONCEPTIONS: GLACIERS S t u d e n t s m ay thi nk ... Glaciers erode by pushing rocks.
Inste ad o f th in kin g. .. Glaciers erode by plucking rocks and through abrasion.
Misconceptions Density and Buoyancy Volume 2, of the Uncovering Student Ideas in Science series contains several assessment probes that can help teachers identify misconceptions about density and buoyancy. Purchase the book at: http:// www.nsta.org/store/ product_detail.aspx? id=10.2505/9780873552738.
Slopingmirror. Photo courtesy of Jeffrey Kietzmann, U.S. Antarctic Program, National Science Foundation
students (such as why icebergs float or why glacial ice appears blue) requires some explanation of density and buoyancy. Although the formal definitions and concepts are beyond gradelevel expectations for elementary school, students can develop informal concepts of density and buoyancy as well as a basic understanding of what types of objects float or sink. What are some of the common misconceptions about these concepts? Many students believe that heaviness is the most important factor in determining whether an object sinks or floats. Students also may think that changing the shape of an object will change its mass or how the object floats. For example, many
students will predict that a long piece of wood will float lower than a short piece of the same wood. Researchers have also found that students investigating floating objects will focus on the object itself and ignore the water or other fluid in which it floats. FORMATIVE ASSESSMENT Icebergs We have followed the model used by Page Keeley and coauthors in the four volumes of Uncovering Student Ideas in Science (ÂŠ 2005-2009 by NSTA Press) and created a similar probe to elicit students' ideas about the effect of melting icebergs on sea level. Melting Icebergs http://onramp.nsdl.org/eserv/ onramp:17106/ Melting_Icebergs.pdf
"Comparing Cubes" asks students to compare properties (mass, temperature, density, ability to float) of a large cube and a small cube made of the same material. It elicits student ideas about whether properties of matter change with increasing mass. "Floating Logs" asks students to predict how a large log and a small one will float in water. It elicits student ideas about whether the size of an object affects its density. "Floating High and Low" asks students to determine how to change how an object floats in water. It elicits student ideas about density and buoyancy. "Solids and Holes" asks students to predict whether an object will float if holes are punched in it. It elicits student ideas about density.
Misconceptions TEACHING THE SCIENCE When Floating Ice Melts in the Sea (Grades 3-5) http://education.arm.gov/ teacherslounge/lessons/ floatingice.stm Students use water and ice cubes to model what happens when floating ice melts. Students (and teachers) will observe that the melting of floating ice, such as icebergs and ice shelves, does not affect sea level. When Land Ice Melts (Grades 3-5) http://education.arm.gov/ teacherslounge/lessons/ landice.stm Students model the melting of land ice (glaciers and ice sheets) to discover that this type of melting does affect sea level.
GLACIERS: Explaining Glaciers, Accurately (Grades 3-5) http://www.nsta.org/store/ product_detail.aspx? id=10.2505/4/sc09_046_08_21 This article from the National Science Teachers Association journal Science and Children describes two activities that help students develop correct understanding of how glaciers change the Earth's surface by plucking and abrasion. Free for NSTA members and nonmembers. DENSITY:
Students make and test predictions about sinking and floating and classify objects according to whether they sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs. Sink It (Grades 3-5) http:// www.sciencenetlinks.com/ lessons.cfm? BenchmarkID=1&DocID=125 Students develop an experiment to test whether objects sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.
Sink or Float? (Grades K-2) http:// www.sciencenetlinks.com/ lessons.cfm? BenchmarkID=4&DocID=164
Lakehoarebeyondcanadagl. Photo courtesy of Dave Haney, U.S. Antarctic Program, National Science Foundation Perito Moreno glacier. Photo courtesy of Matito, Flickr.
Across the Curriculum: Lessons Using Icebergs to Teach Buoyancy and Density By Jessica Fries-Gaither A common misconception among students of all ages is that heavy objects sink and light objects float. While this belief may explain many examples, massive icebergs show that the density of an object, not its weight, is the cause of flotation.
In this article, we've highlighted lessons that allow students to model icebergs and to begin to explore the concepts of buoyancy and density. Although the formal definitions of these concepts are beyond the expectations for elementary classrooms, students should begin to develop an understanding of the types of objects that float and those that sink. Guided activity and leading questions can help students realize that weight is not the only determining factor of whether or not an object floats. Incorporating inquiry-based
MODELING ICEBERGS These lessons all call for the creation of "icebergs" by freezing water in rectangular containers or film canisters. We've also been told by teachers that water balloons are an inexpensive way to create model bergs. Just fill the balloons with water, tie and freeze, and then cut and peel away the balloon when youâ€™re ready to use the models! By using a variety of container shapes and sizes, you can simulate the many types of icebergs. Floating a Bergy Bit (Grades K-3) https://www.cresis.ku.edu/ education/iibLessons/iib012.pdf Students create icebergs and observe that they float in salt water. Floating Ice Volume (Grades 4-5) https://www.cresis.ku.edu/ education/iibLessons/iib013.pdf Students will measure how much ice floats above and below water and calculate its volume.
activity (see suggestions below) can also help students develop an informal understanding of buoyancy and density. All highlighted lessons meet the Physical Science Content Standard of the National Science Education Standards for grades K-4 and 5-8. You can read the entire National Science Education Standards, http:// books.nap.edu/catalog.php? record_id=4962, online for free or register to download the free PDF. The content standards are found in Chapter 6, http:// books.nap.edu/openbook.php? record_id=4962&page=103.
Do-It-Yourself Iceberg Science (designed for Grades 6-8, modify for K-5) http://www.units.muohio.edu/cryolab/education/ documents/MS%20Icebergs.pdf In this inquiry-based lesson, students will experiment with their own film canister "icebergs" to explore the principles of floating icebergs and ice density. The focus on density and calculating volume is too advanced for most elementary students, but the overall experimental design and ideas for further investigation would be useful for most elementary classes. Turn these lessons into inquiry-based activities! Ask students to plan an investigation to determine:
Bergterranova2. Photo courtesy of Mike Usher, U.S. Antarctic Program, National Science Foundation
â€˘ If the shape or size of an iceberg affects whether it sinks or floats
Across the Curriculum: Lessons INCORPORATING LITERACY AND OTHER CONTENT AREAS Incorporating reading, writing, and other cross-curricular activities helps students develop important skills and extends their knowledge. For highquality children’s literature about icebergs, please see Icebergs and Glaciers: Virtual Bookshelf (on page 24).
• If the shape or size of an iceberg affects the percentage of ice above and below the surface of the water • If icebergs float in both salt water and fresh water • If the concentration of salt (salinity) affects whether icebergs float or sink • If the concentration of salt (salinity) affects the percentage of ice above and below the surface of the water
Growing Floaters and Shrinking Sinkers (Grades K-5) http://beyondpenguins.nsdl.org/ issue/column.php? date=August2008&departmentid=literacy&colum nid=literacy!feature Informational text (written at K-1, 2-3, and 4-5 grade bands) explores the concept of floating ice. At each grade band, the text is available in three forms: a text-only pdf, a full-color illustrated book (pdf), and an electronic book with recorded audio (Flash).
Iceberg. Photo courtesy of Rghrous, Flickr
BUOYANCY AND DENSITY While these general lessons don't specifically focus on icebergs, they do help students develop an understanding about sinking and floating by comparing various objects. Students in grades 3-5 use the familiar sinking and floating context to focus on the principles of experimental design. Teachers may wish to combine these activities with the iceberg lessons above to fully develop the concept with their students. Sink or Float? (Grades K-2) http://www.sciencenetlinks.com/lessons.cfm? BenchmarkID=4&DocID=164 Students make and test predictions about sinking and floating and classify objects according to whether they sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs. Sink It (Grades 3-5) http://www.sciencenetlinks.com/lessons.cfm? BenchmarkID=1&DocID=125 Students develop an experiment to test whether objects sink or float. Teachers can incorporate ice cubes into this lesson to focus on icebergs.
What's Happening to the Emperor Penguins? (Grades 3-5) http://www.nationalgeographic.com/xpeditions/ lessons/18/g35/seaspenguin.html Students learn about the habitat and behavior of emperor penguins and consider how icebergs might impact their ability to find food. Summing Up the Disaster (Grades 3-5) http://content.scholastic.com/browse/ lessonplan.jsp?id=198 Students research the Titanic sinking and write and publish a newspaper article.
Science & Literacy: Lessons Hands-on Lessons and Activities about Glaciers By Jessica Fries-Gaither Glaciers can be a difficult subject to teach. Most students haven't ever seen one. Furthermore, glaciers' size and relatively slow rate of change make it difficult to understand how they can change the surface of the earth.
Images from online galleries and children's literature can help students begin to visualize these massive bodies of ice. Creating models will help them develop a basic understanding of the scientific principles at work in glacial formation, movement, and erosion. While many of these lessons are written for the upper elementary grades, teachers of primary students may be able to modify them by performing demonstrations rather than investigations.
GLACIAL FORMATION How Do Snowflakes Become Ice? (Grades K-5) https://www.cresis.ku.edu/education/iibLessons/ iib005.pdf Students model the formation of ice with marshmallows or, if it is available, snow. Lesson extensions suggest using snow cones or shaved ice to model the difference between snow, firn (an intermediate stage between snow and ice), and glacial ice. Glacial Pressure (Grades 3-5) http:// www.teachervision.fen.com/ science/lesson-plan/ 3834.html In this lesson plan, students model glacial formation 20
Many of these lessons and activities lend themselves to making predictions, so we've chosen to highlight that strategy as our literacy integration. Students become proficient readers by making predictions and evaluating them based on the text, much in the same way that proficient scientists make predictions and evaluate based on experimental data. You may choose to have students record predictions on a worksheet or in a journal, or record their oral predictions as you discuss the experiment or text.
through the compression of marshmallows, which represent snow. Students observe the effect of pressure exerted on marshmallows and draw conclusions about pressure exerted on snow. GLACIAL MOVEMENT Blue Ice Cube Melt (Grades K-5) https://www.cresis.ku.edu/education/iibLessons/ iib008.pdf Students experiment with bluecolored ice cubes and learn that ice can melt under pressure.
P1060546. Photo courtesy of jjunyent, Flickr.
Physical Properties of Ice (Grades 3-5) http://www.sd5.k12.mt.us/ glaciereft/glac3-8.htm Students will observe how ice can break or melt under pressure and then refreeze.
Science & Literacy: Lessons Modeling Glacier Dynamics with Flubber (Grades 2-3) http://bprc.osu.edu/ education/lessons/ flubber_activity_grade2-3.zip
INTEGRATING LITERACY Use the books in this month's Virtual Bookshelf (see page 22) and our Feature Story (see page 9) to help your students practice making predictions while reading!
Modeling Glacier It Doesn't Have to End That Dynamics with Flubber Way: Using Prediction (Grades 3-5) Strategies with Literature http://bprc.osu.edu/ (Grades K-2) Massivereflection. Photo courtesy of education/lessons/ http://readwritethink.org/lessons/ Jeffrey Kietzmann, U.S. Antarctic Program, flubber_activity_grade3-5.zip lesson_view.asp?id=87 National Science Foundation. This hands-on activity Primary students listen to the simulates glacial flow. The beginning of a story, and then use students use a glacier-modeling compound made details in the text and prior knowledge to predict from glue, water, and detergent ("flubber") to the way the story will end. predict and observe glacial flow. The students This lesson meets the following NCTE/IRA discuss with the teacher how scientists determine standards: 3, 4, 11, 12. glacial flow with real glaciers. The link opens a zipped file that contains three documents: the Prediction Wheel (Grades 2-5) teacher's guide, notes, and a worksheet. http://forpd.ucf.edu/strategies/stratWheel.html GLACIAL EROSION How Does Ice Break Down Mountains? (Grades 3-5) http://www.sd5.k12.mt.us/glaciereft/ glac23-8.htm In this lesson, students observe how freezing water affects various objects (including rocks).
Students use the prediction wheel template (download a pdf here) to make predictions about what they are going to read, gather evidence to either support or disprove their predictions, and summarize what they have learned. This activity meets the following NCTE/IRA standards: 3, 4, 11, 12.
Explaining Glaciers, Accurately (Grades 3-5) http://www.nsta.org/store/product_detail.aspx? id=10.2505/4/sc09_046_08_21 This article from the National Science Teachers Association journal Science and Children describes two activities that help students develop correct understanding of how glaciers change the earth's surface by plucking and abrasion. Free for NSTA members and nonmembers.
Off The Bookshelf: Polar Oceans: Virtual Bookshelf By Julie Moran While students generally find the topic of icebergs and glaciers captivating, they may have difficulty visualizing and
understanding them. The fullcolor photographs in these books help students begin to develop an understanding of the massive size of some icebergs or a glacier's ability to dramatically change the landscape. Students will also learn about the formation of glaciers and how icebergs calve from them. We suggest pairing these books with the science
and literacy activities found in "Hands-on Lessons and Activities about Glaciers" (see page 20) and "Using Icebergs to Teach Buoyancy and Densityâ€? (see page 18). This month's Feature Story, "Ice Sculptures," (see page 9) discusses how glaciers have changed earth's land over millions of years.
Recommended Books: Icebergs & Glaciers
Icebergs, Ice Caps, and Glaciers. Allan Fowler. 1997. Nonfiction. Recommended Grades: K-1 This resource for early learners describes the characteristics, size, and movement of icebergs, ice caps, and glaciers.
Exploring Glaciers. Melody S. Mis. 2009. Nonfiction. Recommended Grades: 2-4. Did you know that glaciers begin as snowflakes? Glaciers form at different rates; some form in ten years but others take hundreds of thousands of years to form.
Learning about the Earth: Glaciers. Colleen Sexton. 2008. Nonfiction. Recommended Grades: K-2. Simple text and supportive images introduce beginning readers to the physical characteristics and geographic locations of glaciers.
Glaciers. Larry Dane Brimner. 2000. Nonfiction. Recommended Grades: 3-5. This text from the True Book series describes what glaciers are, how they are formed, and how they move and shape the earth.
Icebergs and Glaciers Icebergs and Glaciers. Seymour Simon. 1999. Nonfiction. Recommended Grades: 3-5. Breathtaking photographs mark this introduction to a frozen world of mountaintops and polar regions.
Glaciers. Isaac Nadeau. 2006. Nonfiction. Recommended Grades: 4-5. From the Library of Landforms series, this book will captivate older learners. They will learn that some glaciers are so large they cover entire mountains with ice? Other glaciers are so small they are found tucked away in a shaded hollow on a mountainside.
Icebergs. Stuart A. Kallen. 2003. Nonfiction. Recommended Grades: 5 and up. Designed for older learners, this book contains fascinating information about icebergs. It includes facts about the formation, location, color, and size of these chunks of ice and the animals that live on them.
Glaciers. Sandy Sepehri. 2008. Nonfiction. Recommended Grades: 5 and up. Students will learn about the different types of glaciers, how glaciers move, how glaciers benefit people, life among glaciers, and glaciers and global warming. This resource is filled with photographs, highlighted glacier terms, and fascinating facts.
Recommended Books: Penguins & Polar Bears
If You Were a Penguin. Wendell and Florence Minor. 2009. Fiction. Recommended Grades: K-1. Pictures and rhyming text present some of the many extraordinary things penguins can do. Includes facts about penguins as well as related web sites.
Polar Bears. Amazing Animals Series. Gail Gibbons. 2009. Nonfiction. Recommended Grades: 2-4. Did you know that a polar bear cub weighs about one pound at birth and is no bigger than a small house cat? Polar bears don't stay small for long. During the first month; cubs grow to be four times larger than the size they were at birth. This book also asks the reader a thought-provoking question: should some polar bears be kept in zoos? The zoos help increase the polar bear population, but they also keep bears in spaces much smaller than their normal habitat.
Abo u t U s Beyond Penguins and Polar BearsÂ is an online professional development magazine for elementary teachers. It prepares teachers to integrate high-quality science instruction with literacy teaching. The magazine is available for free at http://beyondpenguins.nsdl.org. Twenty thematic issues link polar science concepts to the scope and sequence of elementary science curricula. The result is a resource that includes issues devoted to day and night, seasons, plants and mammals, erosion, and other physical, earth and space, and life science concepts. Some issues are also interdisciplinary, focusing on polar explorers, the indigenous people of the Arctic, and the challenges of doing science in the polar regions. To browse the complete archive of issues, visit http://beyondpenguins.nsdl.org/archive.php. Other project features include a companion blog (http://expertvoices.nsdl.org/polar) about polar news and research and a social networking site (http://beyondpenguins.ning.com) for elementary teachers to communicate and collaborate with colleagues across the country and around the world. Beyond Penguins and Polar Bears is funded by the National Science Foundation under Grant No. 0733024 and is produced by an interdisciplinary team from Ohio State University (OSU), College of Education and Human Ecology; the Ohio Resource Center (ORC) for Mathematics, Science, and Reading; the Byrd Polar Research Center; COSI (Center for Science and Industry) Columbus; the Upper Arlington Public Library (UAPL); and the National Science Digital Library (NSDL) Core Integration team at Cornell University and University Corporation for Atmospheric Research (UCAR).
Copyright April 2010. Beyond Penguins and Polar Bears is produced by an interdisciplinary team from Ohio State University (OSU), College of Education and Human Ecology; the Ohio Resource Center (ORC) for Mathematics, Science, and Reading; the Byrd Polar Research Center; COSI (Center for Science and Industry) Columbus; the Upper Arlington Public Library (UAPL); and the National Science Digital Library (NSDL). This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Printed version layout and design by Margaux Baldridge, Office of Technology and Enhanced Learning, College of Education and Human Ecology, The Ohio State University.
The enormous size of icebergs and glaciers can spark student interest - and questions. How can huge icebergs float? How do massive glaciers...
Published on May 11, 2010
The enormous size of icebergs and glaciers can spark student interest - and questions. How can huge icebergs float? How do massive glaciers...