Understanding Balance
In this lesson, children will explore balance and the center of mass.
Learning Goals:
This lesson will help children meet the following educational standards:
- Demonstrate curiosity about the world and begin to use the practices of science and engineering to answer questions and solve problems
- Explore concepts and information about the physical, earth and life sciences
- Understand important connections and concepts in science and engineering
Learning Targets:
After this lesson, children should be more proficient at:
- Using nonstandard and standard scientific tools for investigation
- Becoming familiar with technological tools that support scientific inquiry
- Using a balance to measure weight, using nonstandard units
Step 1: Gather materials.
- The book, Room on a Broom, by Julia Donaldson
- A wire hanger with a straight edge
- Scissors
- Tape
- Three pieces of string, yarn or pipe cleaners cut to the same length
- Three yogurt or plastic or paper containers of equal size
- Three small items of different weights (make sure these items will fit into the containers and are light enough for the string and tape to hold)
Step 2: Introduce activity.
- Read Room on the Broom
- Ask the children: "How do you think the witch and the animals stay on the broom while it is flying through the air? Is it the same as when we balance on a bike or on one foot?"
- Explain: "We balance ourselves by shifting our weight to the other side."
- Ask the children to stand on one foot while discussing the following question: "What happens when we are trying to balance and we start to wobble and fall to one side?"
- Say: "To balance, what we put on one side of a center point must be equal to what we put on the other side of the center point."
Step 3: Engage children in lesson activities.
Show the children how to create their own balances:
- Attach one piece of string to the bottom of a container with tape. Run the string up the side of the container and secure it with sticky tape below the brim. Loop the string through the triangle of the hanger, then attach the string to the opposite side of the container, on the bottom and below the brim.
- Say: "The hanger works like a balance or a seesaw. When we put a container on one end of the hanger, gravity pulls it down more in that direction. To balance the hanger, we need to hang an item of the same weight on the other side of the hanger."
- Attach a second container to the hanger.
- Place your hanger on a doorknob or door handle.
- Push the containers to opposite ends of the hanger—as far as they will go. Your hanger should hang straight if it is balanced. Ask the children: "Is your hanger balanced? How can you tell?"
- Put one toy in each container. Ask: "Is the hanger balanced now? How can you tell?"
- After placing toys of different weights in the containers and pushing the containers to opposite ends of the hanger, ask: "Which toy is the heaviest?" Slide the heavier container along the coat hanger until the toys are balanced. The hanger will be level when the toys are balanced.
- Then ask: "How far along the hanger do you need to move the container until it is balanced?"
- Try this activity again with two different toys.
Step 4: Engineering vocabulary
- Balance: An instrument used for measuring mass or weight
- Counterbalance: To equal or make equal in weight, number or proportion
- Heavier: Having greater weight
- Lighter: Having less weight
- Heaviest: Having the greatest weight
- Lightest: Having the least amount of weight (e.g., "Which object is the lightest?")
- The same: Identical in kind or quantity (e.g., "Both objects weigh the same.")
- Weigh: To measure according to weight (e.g., "Which object weighs more?")
Suggested Books
- Balancing Act by Ellen Stoll Walsh
- Forces: Physical Science for Kids by Andi Diehn
- Scoop, Seesaw and Raise: A Book About Levers by Michael Dahl
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