Balancinq acts

Science World, May 12, 2008

After reading "Under the Big Top" (p. 12), set up the following activity stations. Then, have students try each activity to learn more about balance.

STATION 1:

Set a desk near a wall and place a card with the following instructions on the desk:

Instructions: Press the right side of your body against the wall. Make sure your right foot is as close to the wall as possible. Try to lift your left foot sideways. Were you successful? Why or why not?

STATION 2:

Place a chair near a desk and place a card with the following instructions on the desk:

Instructions: Sit in the chair. Keep your back straight and pressed into the chair. Keep your feet flat on the floor, your knees at 90[degrees], and your arms crossed over your chest. Try to stand up. Were you successful? How might you shift your center of gravity to allow you to stand up?

STATION 3:

Place a meter stick and a card with the following instructions at the station:

Instructions: Place your hands together with one palm facing the other: Have a partner balance a meter stick horizontally across yore hands. Then, remove one of yore hands. Try to balance the meter stick on one hand. What do you need to do to keep the meter stick balanced?

STATION 4:

Place a bag of pipe cleaners, a bag of Popsicle sticks, a box of hex nuts or a tub of clay, and a card with the following instructions at the station:

Instructions: Use 2 pipe cleaners, 2 Popsicle sticks, and hex nuts (or clay) to create a structure that will balance on the end of your finger. Draw a diagram of your structure, and place an "X" where you think the center of gravity is located.

CONCLUSIONS:

Have students answer the following: Were you able to complete all of the activities successfully? Why or why not? Is the center of gravity always in the center of an object?

TAKE IT FURTHER:

Have students use found objects to create kinetic' mobiles. For ideas, check out: www.creativity-portal.com /howto/artscrafts/mobile.html

Station 1: If students followed directions, they should not have been successful in lifting the leg. That's because when you lift a leg, the top half of your body usually leans toward the opposite direction for balance. The wall prevents the body from leaning.

Station 2: If students followed directions, they should not have been able to stand up. To stand up, students would need to lean forward to move their center of gravity.

Station 3: The meter stick's center of gravity should be located at the center of the stick. Students need to adjust their hand or the stick so that the stick's center rests on the hand.

Station 4: The structures will vary

Conclusions: Answers will vary The center of gravity is where an object's weight is evenly balanced, It isn't always located in the center of an object

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