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Introduction LEGODACTA® LeverSet
This booklet hasbeen developed by teachers to support and guide you and your students through your exploration of the LEGO DACTA Lever Set, #9612. The booklet contains: • Information about levers • Simple hands-on lever activities • Drawings of possible solutions
Activities for exploring concepts (pages 3-7), investigating principles (pages 9-11), and solving problems (pages 12-15) are included for elementary school students of varying abilities. The activities foster and enhance cooperative learning in teams of two students per building set.
After performing the activities in this booklet, students will be able to: • Define a lever as a rod or arm that tilts around a pivot to produce useful motion. • Describe the fulcrum, effort, and load (or resistance) of a lever. ▪ Build models of devices which incorporate three different classes (or types) of levers. • Recognize that the effectiveness of a lever depends on the arrangement of the fulcrum, effort, and load. • Have fun with levers!
LEGO and D AC T A are tr admalk s o ld ie L EG ( ) Group. D is [tibuted by the L EGOGr o u p . D K-7190 Ba w d , Dcmnark. 0 1997 The L EG G Group, ISBN 0-91453I-83-C.
LeversinAction A lever is a rod or arm that tilts around a pivot to produce useful motion. One of the ti o simple machines, the lever can make work 0 easier by amplifying motion or force, 6 or by changing the direction of a force. a Here are some examples of levers or devices made up of levers, The three classes of levers are discussed on pages 4-7. Seesaw (1st class), • Scissors (connected 1st c1ass)-3 • Wheelbarrow (2nd class),3 • Nutcracker (connected 2nd class)e3 • Fishing rod (3rd class) .q 111Tweezers (connected 3rd class)) • Nail clippers (2nd class and 0 connected 3rd class) Photographs on the back of this booklet show other examples of how levers make work easier.
The diagram at the lower right shows the various parts of a lever in general. The load is moved by the effort (a push or 0 pull) making the lever tilt about the fulcrum 0 (pivot).
Familiarize yourself with levers by working through activities on pages 4-7. Photocopy the drawings on pages 16-17 for easy reference. You may wish to provide these activities to your students as well.
LeversinAction FirstClassLever â€˘ Build the base and model 1 shown on page 16. Predict what happens when you 11122 down at t _ l i e e l l o N 1 the handle. As you push down (effort), the beam tilts about the axle (fulcrum) and lifts the weighted brick (load). â€˘ Predict what hap ens w S l i down on the handle closer to the fulcrum._ You also Igt the weighted brick, but you have to push down with more force,
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MainIdeas: A first class lever has the fulcrum between the effort and the load. It is easier to lift a load with a first class lever if you push down at a point far from the fulcrum.
AdditionalInformation: First class levers are often used to change the direction of forces. A seesaw is an example of a first class lever. First class levers can also be connected to each other, as in a pair of scissors.
Extension: Switch the places of the yellow tile and the weighted brick. Repeat the above investigation. Then change the lontion of the brick along the beam. ( A ) ' A t e t a a (It takes a great effort to raise the brick, because you are pushing down so close to the fulttum. However, as the load is also moved closer to the fulcrum, the effort needed becomes less.)
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LeversinAction SecondClassLever • Build model 2 shown on page 17. Predict what happens when you push up_al the yellow tile on the handk. As you push up (effort), the beam tilts about the axle (fulcrum) and lifts the weighted brick (load).
• Predict what happens when you push up on the handle closer to the fulcrum. You also lift the weighted brick, but you have to push up with more force.
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MainIdeas: A second class lever has the load between the fulcrum and the effort. The effort will always be less than the load. The farther from the fulcrum you apply the effort, the easier it is to lift the load.
AdditionalInformation: Second class levers are often used to lift heavy loads or to apply large forces. A wheelbarrow is a typical example of a second class lever. Second class levers can also be connected to each other, as in a nutcracker. RO •ts T
)Extension: Move the weighted brick closer to the yellow tile andL rOe p t t investigation. t takes more effort to raise the (it k a bas l sitpisr moved e load further from the fulcrum. When the load is closest to the fulcrum, it can be lifted with the least effort.)
LeversinAction ThirdClassLever â€˘ Build model 3 shown on page 17. Predict what happens when you push up on the handle at the yellow tile. As you push up (effort), the beam tilts about the axle (fulcrum) and lifts the weighted brick (load).
the handle to the fulcrum. â€˘onPredict what closer happens when you push up You also lift7he weighted brick, but you have to push up with more force.
MainIdeas: A t hird class lever has the effort between the fulcrum and the load. The farther f rom the fulcrum the load is located, the more effort you will have to apply to lift it.
AdditionalInformation: Although third class levers can be used to lift loads or apply specific forces, as in a stapler, they are also used to amplify motion. A fishing rod is a typical example. The fulcrum is the hand at the end of the rod handle. A small motion of your other hand produces a large movement of the rod tip. Third class levers can also be connected to each other, as in a pair of tweezers.
First Class Lever
FirstClassLevers The fulcrum is between the effort and the load. A seesaw is an example of a simple first class lever. A pair of scissors is an example of two connected first class levers. load f u l c r u m e f f o r t
Second Class Lever
The load is between the fulcrum and the effort. A wheelbarrow is an example of a simple second class lever. A nutcracker is an example of two connected second class levers. fulcium
Third Class Lever
The effort is between the fulcrum and the load. A stapler or a fishing rod is an example of a simple third class lever. A pair of tweezers is an example of two connected third class levers.
load effort f u l c r u m
To lift a load with the least effort: â€˘ place the load as close to the fulcrum as possible. â€˘ apply the effort as far from the fulcrum as possible.
May be photocopied for student work. See page 3.
Cause and effect Predicting
Measuring Problem Solving Inferring Communicating
Gathering and recalling information Understanding and interpreting data and information Applying what is learned to solve problems in new situations Analyzing a problem into its component parts Synthesizing various aspects or components into a new whole to solve a problem Evaluating one's own wort
NotesforBuilding CardI Students can investigate connected first and third class levers using Building Card I from their Lever Set. Instructions for your students appear below. Answers are shown in parentheses.
Build the model of the pliers through step 2. • How does this model use levers? (Two first class levers are connected to a common fulcrum. The effort is applied at the ends of the handles. The load is picked up by the other ends.) • Use the model to pick up several different objects. Gently pinch your finger with the model to feel how much force it can apply. Easy does it! • Change the position of the connector peg in the model as shown in step 2A and repeat your investigation. How is this model different? (This model can apply a little more force because the fulcrum is closer to the load.) • Move the connector peg to the ends of the handles as shown in step 2B and repeat your investigation. How does this model use levers? (Two third class levers are connected to a common fulcrum at the ends of the handles. The load is picked up by the other ends and the effort is applied in between. This model applies less force because the load is far from the fulcrum.) • Build the model shown in step 2C on your card. This model consists of two pairs of connected first class levers. Use the model to pick up several different objects. How far can it reach? • Build the model in step 2D, adding the dragon parts as shown (see page 18), Predict what happens when the model is operated. (The jaws and tail move.) Invite students to design and color a dragon body to add to the model. (4/ 4
NotesforBuildingCard2 B u i l d Students can investigate first and second class levers using Building Card 2 from their Lever Set. Instructions for your students appear below. Answers are shown in parentheses.
Build the first model, following the instructions through step 6. How does this model use levers? (A first class lever is attached to an upright beam with a tray on top. Other beams parallel to the lever keep the tray upright.) • Predict what happens if you place a small object on the tray. Then test your prediction with several different objects. (The object (effort) makes the tray sink down, The other end (load) of the long beam rises. The heavier the object, the higher the long beam rises.) • How can this model be used? (The model could compare the weights of different objects.) • Change your model as shown in step 6A by adding the weighted brick to the end of the long beam and attaching a cardboard scale (see page 18) to the upright beam. Predict what happens if you place a small object on the tray. Then test your prediction with several different objects. (The device still functions as above. The beam does not rise as high for the objects used earlier because their weight does not push down enough to raise the weighted brick as much.) • How can this model be used? (This model can be used to compare the weights of heavier objects. Different cardboard scales could be designed to determine the weight of objects.) • Change your device into a press as shown in step 613. How does the press use a lever? (When you pull down (effort) on the handle, the beam pushes down (load) to press the base. This is a second class lever.) How could the press be used? (Students can suggest many uses, including pressing plates onto other beams.)
d i n g CardExtensionsIdeas BuildingCard I What other animals or figures could your students invent for the model in step 2D? Set up a display to show off the work of your imaginative students. Convert the skeleton of the model in step 2D into a weighing device to lead into Building Card 2. Place the weighted brick as shown in the drawing on the right. Test the device with several small objects. Ask each of your students to construct a simple pair of "scissors" using two long beams and one gray connector peg. Challenge students to find a way to connect their models together end to end to make a super-long extender, How far will it reach? What will it pick-up?
BuildingCard2 Suggest that groups of students use two devices from step 6 together to weigh objects. Challenge them to predict what happens if they place a yardstick or meter stick across the trays of two devices at once. (if the stick is supported at the ends, each device will support half the weight. I f one of the devices is moved nearer the middle of the stick, it will support more of the weight) Invite students to use their device from step 6 B as a catapult to launch balls of paper. How consistently can they flip their paper balls into the trash can? What class of lever is the catapult? (The catapult is a first class lever The rubber band provides the effort, and the ball is the load.)
Aunt Monica has dropped her glasses and is having difficulty picking them up. She needs some help. Design and build a picker-upper which: • can be operated with one hand. • can pick up the weighted brick.
SOLVING COPYMASTER I
A series of connected levers works well for this problem. Sample solutions are shown below. Students might want to use a rubber band to keep the pincers open or closed.
Students can make use of extra rubber bands, string, and assorted small objects.
Can the weighted brick be picked up? Judge how easily the device can be operated with one hand.
Modify the device so it can pick up a sheet of paper,
Linda needs a way to control the cows as they cross the railroad on their way into the barnyard. Design and build a lever device which: • can keep the cows from crossing the railroad tracks. • can be raised and lowered. • can be locked in the raised and the lowered position. 14
In the sample solution below on the left, note the counterweight (extra beams and plates at the right end of the barrier beam). When you push down on the counterweight, the beam acts as a first class lever and raises up easily. The two axles shown can be used to lock the barrier in the raised and in the lowered positions. When you raise the barrier beam as shown in the drawing on the right, the beam acts as a second class lever.
Students may want to use small animal figures.
Does the barrier lock in both the raised and the lowered positions? Judge how easily the barrier can be operated.
Change the device so that the barrier is as long as possible.
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MAYBE PHOTOCOPIED FOR STUDENT REFERENCE
Building ElementSurvey 0
6 each, I x 2 beam, red 2 each, 1 x 4 beam, red 2 each, 1 x 6 beam, red 4 each, 1 x 16 beam, red 1each, 2 x 6 weighted brick (54 grams), black 6 each, connector peg, gray
O r 10 each, friction connector peg, black 0 00' 0 c 12 , e 0 artt 4 c A he ° , I a e x a l c e h 4 , s lit a ist t ax u nl . a0 d oe s ,6 l1 os o ,t• • nC D 1u g ed , as b cl l
8 each, bushing, gray
2 each, I x 2 plate, yellow 2 each, 1 x 3 plate, yellow 2 each, 1 x 6 plate, yellow 5each, 2 x 2 plate, yellow 2 each, 2 x 6 plate, yellow
4 each, 2 x 2 flat tile, yellow I each, 2 x 2 angular plate, red 1 each, rubber band, black
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