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This is an amazing STEAM activity for kids! They will be amazed as the toothpick stars they create magically expand before their eyes when you add water to them. It’s another easy activity that only requires a few materials that you probably already have at home.
The most difficult part of this activity is breaking the toothpicks in half. Older kids can do this step on their own, but an adult will have to do this step for younger kids. It took us several tries to work out how to break the toothpicks just right.
The key is to break the toothpick as close to the middle as possible, but this is easier said than done. Also, you can’t break apart the toothpick completely, you want it still attached in the middle after the break.
We went through more than double the toothpicks we used in the activity while learning how to break them just right, so be sure to have extra toothpicks on-hand. It takes a little trial and error, so don’t get frustrated and give up if you can’t break it right on your first few tries.
The hard work breaking the toothpicks was worth it after we made the stars. My kids were amazed watching our toothpick stars expand. We tried stars of several different shapes and sizes and we encourage you to experiment with it too! You don’t have to just do the simple 5 point star outlined in the procedure, feel free to try different shapes and sizes of stars.
This activity was inspired by this video on one of my favorite Instagram accounts @emilia.science.
Watch the Activity:
We made both a YouTube video and Instagram Reel for this activity. They are different videos, so you can watch both for more examples and a different take on the activity. Check them out below.
Watch the YouTube video here:
Watch the Instagram reel here:
Activity Overview:
In this activity kids will watch a star “magically” expand before their eyes just by adding water. Big kids can set this up on their own, and an adult will have to set up for younger kids (breaking the toothpicks is more difficult than it seems). This activity is recommended for children ages 3+.
Materials:
- Toothpicks
- Plate
- Small cup of water
- Dropper
Safety:
Toothpicks are sharp and can poke or prick skin. Use caution with the toothpicks and advise kids to not purposely press toothpick tips into skin. The broken edges of the toothpicks can be sharp and cause splinters. Do not touch the rough, broken end in the middle of the toothpicks.
I recommend setting down a table cloth or placemat before beginning this activity. This will help protect your table from accidental water spills. Have extra towels on hand to clean up any water spills to prevent slips or falls.
Once you are done with the activity, drain the water in the sink then dispose of the toothpicks in the trash, or you can compost them because they’re biodegradable, just don’t dump them down the sink!
Procedure:
- Break five toothpicks in half, but not completely separated. They should still be attached at the center. You want them broken as close to the middle of the toothpick as possible. It may take serval tries to get it right.
- Arrange the five toothpicks into a closed star shape on the plate, with the sides touching each other (see photo below for reference).
- Fill a dropper with water.
- Slowly release the water into the center of the star and watch as the star begins to expand.
- Repeat, testing different sizes and configurations of stars. We made 5, 6, 7, and 8 pointed stars.
STEAM Concepts Learned:
The main driver of the “magical” movement in this activity is capillary action. The dry toothpicks absorb the water through capillary action. As the toothpicks adsorb water the capillary pressure causes them to expand and try to straighten. As the toothpick straightens, it exerts a force on the neighboring toothpick. This force causes the star to expand, looking like it is opening wider.
This is a fun and simple STEAM activity that is a great boredom buster for older kids. We enjoyed this activity and it kept us busy for a long while as we learned to break the toothpicks, and then tried many different shapes and sizes of stars.
Let us know what size stars you try and how this works for you!
