Toothpick Stars For STEM

Is it magic or is it science? Either way this toothpick star STEM activity is sure to impress! Make a star out of broken toothpicks by only adding water. Learn about capillary action with a totally do-able science activity for home or in the classroom. It could even be your next toothpick party trick!

BROKEN TOOTHPICK SCIENCE FOR KIDS

WATER TOOTHPICKS

Our toothpick star trick is a fun example of capillary action at work. We love simple physics experiments and have been exploring science for kindergarten, preschool, and early elementary for almost 8 years now. Make sure to check out our collection of simple science experiments for kids!

Our science activities are designed with you, the parent or teacher, in mind! Easy to set up, quick to do, most activities will take only 15 to 30 minutes to complete and are heaps of fun! Plus, our supplies lists usually contain only free or cheap materials you can source from home.

Grab some toothpicks and a water dropper, and let’s find out what happens when add them together! Do you think you can make a star from broken toothpicks without touching them? Try this fun science activity and find out. Make sure to read up on the science behind it too!

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STAR TOOTHPICK TRICK

SUPPLIES:

5 toothpicks
Small plate
Small bowl of water
Medicine dropper

INSTRUCTIONS:

STEP 1. Take the 5 toothpicks and bend them until they bend in half but be careful not to let them break fully apart.

STEP 2. Arrange the toothpicks so they create a closed star pattern as seen below.

STEP 3. Fill up the medicine dropper with water.

STEP 4. Slowly add drops of water to the center of the toothpicks and watch the star move!

HOW DOES IT WORK?

The toothpicks are made of dry wood. When water is placed in the middle of the closed star, the wood starts to absorb the water, which makes the wood expand. But how does the wood absorb water?

The adhesive forces between the water and the wooden toothpick are stronger than the cohesive forces inside the water itself. This adhesive force pulls the water molecules into the narrow spaces within the wood.

This process is called capillary action. The result is that the water travels to the tips of the broken toothpicks.

As the wood absorbs more of the water, the bent wood fibers expand and straighten out. Then each toothpick pushes against the others. As the toothpicks straighten, the inside of the star opens up.

Capillary action can also be seen in plants. It’s how plants move water from their roots to the leaves. Here are a few other activities that demonstrate capillary action at work…