Grade Level: 1-4

Purpose: Students will recognize that body design affects balance.

Skills: Observing, communicating, investigating, inferring, making a model

Standards: Communicates about investigations; understands that learning can come from careful observations and simple experiments; recognizes how factors such as gravity can affect common objects; describes an observed change in terms of starting conditions, ending conditions, using words, simple diagrams, or graphs; Identifies what does and does not change when matter experiences an external influence such as push, pull.

Background: Gravity is a force that all living organisms have to deal with. The body structure of animals is a system of balanced beams and masses. In order to stand or walk, animals like dinosaurs must balance on their feet. To do this, they must keep their center of gravity "between" their feet. The center of gravity is the balance point of a body. When you balance a ruler on your finger, the center of gravity is right under your finger.


For each student: lab sheet, rulers, scissors, plastic straws, large marshmallows (8 each), small marshmallows (4-10 each), dinosaur models and/or pictures


Discuss center of gravity. Have each student find the center of gravity of a ruler.

Explain that the bodies of animals must be balanced or they will fall over due to the pull of gravity. Have students try leaning way over. What do they find themselves doing to prevent themselves from falling over? When they stick out an arm or leg, they are using a counter balance for the part of the body that is leaning away from the center of gravity. That way, gravity pulls down on both parts of their body equally.

Tell students they are going to investigate the basic structure of a dinosaur body to see how it achieved balance. Give each student the lab investigation sheet, scissors, 4 straws and 8 marshmallows. After they have completed their investigations, let them build any dinosaur body system they want, using small marshmallows and extra straws as needed. They should plan it out on paper, so they know how many small marshmallows and straws they will need. Have them share with the class how balance is achieved in that body system. They could look at models or pictures of dinosaurs for ideas.
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Purpose: to find out how a dinosaur body system was balanced

Materials: scissors, straws, marshmallows

Part 1: Checking out a bipedal dinosaur like Tyrannosaurus rex. Build a model of the hips, legs, and feet of a bipedal dinosaur. Use one straw cut in half and 3 marshmallows. Make sure the system is balanced. Cut one straw into 4 equal pieces. Use one short piece of straw and a marshmallow to add a head to your model. Write down what happens.

Use one short piece of straw and a marshmallow to add a tail to your model. When you have your model balanced, draw a picture of it with circles and lines.

Part 2: Checking out a quadrapedal dinosaur like Morris the Saurus.
1) Take the head and tail off your bipedal dinosaur. Add shoulders and two more legs, using a half straw, two short pieces of straw and one marshmallow. Why is this body structure more stable?
2) Using one marshmallow and a half straw, add a head to the body. What happens? Why?
3) Make this dinosaur body system balanced. Then draw a picture of it.
4) What makes a body system balanced?