Beacon Lesson Plan Library

Making Tracks

Leon Mays

Description

Students make casts of animal tracks, identify, and explain how the animal's feet are adapted for their function.

Objectives

The student knows that body structures are uniquely designed and adapted for their function.

The student knows that scientists assume that the universe is a vast system in which basic rules exist that may range from very simple to extremely complex but scientists operate on the belief that the rules can be discovered by careful, systemic study.

Materials

-Plaster of Paris
-Containers for mixing
-Spray shellac or spray plastic
-Petroleum jelly such as Vaseline
-Cardboard
-Knives
-Sandpaper
-Black ink or paint
-Water in jugs

Preparations

1. Collect plaster of Paris, containers for mixing, shellac or plastic, petroleum jelly, cardboard, knives, sandpaper, and black ink.
2. Collect a plaster of Paris cast track from a different location such as the seashore to present to the students for assessment.
3. Collect resources (books, charts, etc) for discussion of prior knowledge.

Procedures

Prior to the activity, introduce the activity to the class and make available research material for discussion of the characteristics of tracks. Demonstrate the correct way to collect tracks by making a cast of a student's hands.

1. Take the class on a field trip to a nearby lake, stream, or wildlife refuge area, or anywhere there will be lots of tracks.

2. Divide into small groups to find tracks. Students may be divided into groups according to areas in which they will look for tracks, such as, one group will look under bushes, one group at a meadow's edge, one group near a pond's edge. Prepare the students in advance to assist them in looking carefully and responsibly.

3. Once a track is found, clean it of loose particles of soil, twigs, leaves, and other litter.

4. Spray the track with shellac or spray plastic being careful not to spray too close and perhaps blow details from the track.

5. Form a two-inch wide strip of cardboard into a ring surrounding the track. Press firmly into the ground to give support, but allow at least one inch to form the edge of the mold for the plaster. (Cutting milk cartons horizontally can make square forms.)

6. Mix about two cups of plaster of Paris in a tin can or plastic bowl, by adding water slowly until it is about as thick as heavy cream. Pour carefully into the mold until the plaster is about to the top. Allow plaster to harden at least 15 minutes before lifting it out of the track. If the soil is damp, hardening may take longer.

7. When the cast is hardened, lift the cast out, remove the ring, and clean the cast by scraping it with a knife blade and washing. (This may be done back in the classroom)

8. Back in class, apply a thin coating of petroleum jelly to the track and surface of the cast. Place it on a flat surface and surround the casting with a two-inch strip of cardboard as before.

9. Mix plaster of Paris and pour into mold, making certain that the top surface of the casting is smooth and level with the mold. Allow two hours for plaster to harden.

10. Carefully remove the mold when the plaster is dry. Separate the two layers and wipe the excess Vaseline from the face of the cast and track. Scrape any rough places with a knife blade, or use fine sandpaper to smooth the surface. Wash the completed cast in running water.

11. When the cast is thoroughly dry, paint the inside of the track with black ink or black poster paint. A coat of clear shellac or clear plastic may be applied to protect and preserve the casting.

12. Once all casts have been finished, students will list three characteristics of the animal track. Ask students to compare the tracks and list similarities. Students may identify that all mammals have basically the same foot structure.

13. Have students identify the prints by their characteristics. (Resource materials may be used.)

14. Ask students how the prints are different. Lead students to see that the animal's foot has adapted for a particular function. For example, we find that some animals (carnivores) walk on their hands-like raccoons and bears. They use their front feet to catch and eat their food. Others walk or run on their toes, like cats and coyotes, while some walk on their toenails or hooves like deer and elk.

Assessments

The following list may be used for assessment. Points will be awarded for completion of each area.

___1. Did student listen to discussion?
___2. Did student watch the demonstration?
___3. Did student create a cast?
___4. Did student cleanup material?
___5. Did the student list three similarities from casts taken?
___6. Did the student list three differences from casts taken?
___7. Was the student able to make a prediction about how the animal lives--food, habitat, size, etc.?
___8. Did the student use reference materials to check the prediction for accuracy?

___Bonus - Identify the cast that the teacher brought, according to the unique design, similarities and characteristics.Use the knowledge that was gained by observing the casts collected on the field trip.
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