Learn about balance and center of gravity with a simple engineering challenge!
Simple building and engineering challenges are so much fun for kids! If you’ve been following this website for very long, you know that we love open-ended STEM challenges with simple materials. They’re a great way for kids to build fine motor skills, learn about physics principles, and grow their creativity, all while having FUN.
Here’s a great way for kids to explore the concepts of balance and center of gravity. Create some awesome feats of balance with a basic craft supply that you probably already have – craft sticks!
Crazy Balancing Craft Sticks Set-Up
- Building blocks or something similar
- A dowel rod with flat sides
- Household items to balance – pen, scissors, fork, etc.
- Craft sticks
- Items to add weight – wooden cubes, LEGO bricks, etc.
This set-up we used for this STEM challenge is quite simple. It’s just a rectangular dowel rod balanced on wooden building blocks. If you don’t have blocks, you can use stacks of books.
I found this rectangular (flat sides) dowel at Hobby Lobby, and you should be able to find one at any major craft store. This one was in the aisle with wood crafts in a bin with different sizes of dowel rods. They are also available at hardware stores, such as Lowe’s and Home Depot.
Beyond the dowel, supplies needed are craft sticks and objects to use as weights. We used wooden cubes (also from Hobby Lobby), LEGO bricks, and various items from around the house.
Finding the Center of Gravity
It works well to start this lesson by showing kids how to find the balance point or center of gravity of an object.
The balance point of an object is the spot in which the object will balance when placed on a fulcrum. In this case, the dowel rod is the fulcrum. The forces on both sides of the fulcrum must be equal in order for the object to balance. So if one end of the object has more mass, you’ll need to compensate by moving the fulcrum closer to that end.
My 7 year old enjoyed this project. It stretched her coordination to balance the objects just right!
After we tried balancing several objects, and realized that the balance point of irregularly shaped objects is not right in the center, we started exploring balancing craft sticks with weight on the ends.
A craft stick will balance right in the center since the mass is equal on both sides. Add a wooden cube (or a LEGO brick) to each side. It should still balance in the middle because the weight is balanced!
(By the way, this is ALGEBRA. I’m not joking! We did the same thing to both sides of the equation, so the sides are still equal!)
What happens if we add DIFFERENT amounts of weight to each side?
If we add two wooden cubes to one side, we have to move the fulcrum REALLY close to that side. But it still balances! If we add two cubes to one side and one cube to the other side, we have to move the fulcrum closer to the heavier side. But not as far!
TIP: If you’re doing this activity with young kids (under age 8) you might want to glue the cubes to the craft stick. This allows for less exploration, but it’s hard to balance the stick AND keep the stuff from falling off! But older kids will be able to do it.
For a class, you could assemble several sticks ahead of time with weight added in various places. Let the kids experiment with balancing the sticks!
Balance with LEGO Bricks
LEGO bricks work well for balancing because they stick together. A 2 x 4 brick is equal in size to two 2 x 2 bricks, so we wondered if three 2 x 4’s would balance with six 2 x 2’s. They almost balanced! The fulcrum was slightly closer to the stack of 2 x 2’s, probably because there is more plastic involved. Two 2 x 2’s have more sides that one 2 x 4.
It was fun finding a way to balance 8 bricks against 1!
Need more Engineering Challenges for Kids?
Make working gears out of popsicle sticks, build a straw roller coaster, make a popsicle stick catapult, launch a bottle rocket, and more! See all the projects here: 30+ Engineering Challenges with Simple Materials