Make a Simple Balance Toy
In this STEM activity, little scientists make a simple balance and explore weight, balance, design and center of gravity.
The simple explanation: when things are balanced, it means things are equal. When the weight is equal on both sides of the balance, the balance stands up straight. When you add weight to one side or the other, it tips!
Gravity is an invisible force that pulls everything down toward the Earth. An object’s balancing point is the same thing as its “center of gravity”. That’s the place where you can hold up an object (with a finger, for example) without it falling over on one side or the other, and is the spot where gravity is pulling down all around an object with the same force. Note: the center of gravity isn’t always in the center of the object! Try balancing a knife for example. . . .
- disposable plate - 1 of this item per student
- very small disposable cups - 2 of this item per student
- tape - class set
- sheets of red & pink paper - 1 of this item per student
- markers - class set
- candy hearts or similar (optional)
Cut out three paper hearts for decoration. Write "Hugs" on one heart and "Kisses" on another (or similar).
Cut the disposable plate in half. (Styrofoam plates work best because they are the most sturdy.) Drawing a line for little scientists to follow is very helpful, as cutting in the center is critical to making this project work.
Tape the halves back to back along the cut edge. Be sure the curve of the outside of the plate flares OUT at the bottom, not in. This will help the balance to stand up. If the balance doesn't stand up well, trim the bottom until it is fairly even on all sides.
Tuck a small disposable cup in the cavity created at each end of the top of your balance; tape in place. (See video!)
Tape the "Hugs" and "Kisses" hearts over the cups. Tape the third heart in the center of the balance for decoration. Kids can also add their own creative designs if time permits.
If your fully-constructed balance won't stand up or lists to one side, you'll need to re-engineer. What is off balance? Is something heavier on one side? Make this part of the learning experience!
To play with your balance, add candy hearts or similar to each of the cups. How does this affect the balance?
- Try using lots of different sizes, shapes and weights of objects to test the balance. This helps scientists observe that sometimes smaller but more dense objects weigh more than larger but less dense objects.
- Try finding the center of gravity on many different objects, especially ones that are not symmetrical, such as spoons. It is fun for kids to discover that the center of gravity isn't always in the center!