Today’s STEAM Activity is learning about the law of inertia using a coin trick. My kids got quarters, dimes, nickels, and pennies in their plastic eggs from the Easter bunny. My son has been learning about change at school and was so excited to get more for his piggy bank. I thought this activity would be a great opportunity to learn and play with their coin collections. 


  • Tall clear cup
  • Water
  • Small piece of cardboard 
  • At least 5 coins (quarters worked best for us)


  1. We started by learning about pennies, nickels, dimes, and quarters. I asked the kids to count out ten of each coin. Then we talked about how much each coin is worth and counted how much ten of each coin is worth. 
  2. Ask the kids to make a pile of 5 coins and set aside
  3. Fill a cup about 3/4 full with water
Step 1
Step 2
Step 3

4. Place a piece of cardboard over the cup with a small hang over in the front
5. Place a stack of 5 coins on the cardboard, centered over the cup of water
6. Flick the cardboard as hard as you can sending it flying back off the cup. The coins should all drop down directly into the cup of water below! 
* We found it helpful to practice “flicking” technique by practicing flicking the cardboard off the cup without the coins first. Once my kids figured out how to flick it hard and quick, then we added the coins. It’s not as hard as it might look, both my 5 year old and 3 year old were able to do this activity!

Step 4
Step 5
Step 6


  • Science: A fundamental physics concept is the principle of inertia used to describe the motion of objects and how they are affected by applied forces. The law of inertia is the resistance of any physical object to any change in its state of motion. It is further defined in Newton’s first law of motion: objects in motion will stay in motion and objects at rest will stay at rest unless acted on by an outside force. In our case the cardboard and coins are at rest. The flick is the force that sends the cardboard into motion, but this force was not acted on the coins. Instead, gravity drops them straight down into the cup below. 
  • Math: Ask your kids to stack and count coins by 5 and/or 10. For kids in kindergarten and above, ask them to count the monetary value of their stack of coins (for example: 5 quarters is $1.25). 

We had so much fun with this activity. It’s a great opportunity to take fun slow motion videos. We laughed so hard at the videos when we watched them. The flick and subsequent fall of the coins happens so quickly you need the video for proof it actually happened! 

I hope you give this a try and have as much fun as we did!


Some of the links below are affiliate links, which means that if you click on a product link I may receive compensation at no additional cost to you. I only link to products and pages I personally use and highly recommend. As an Amazon Associate I earn from qualifying purchases. Thank you for your support!

You have Successfully Subscribed!