Magic Rainbow Toothpick Star

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This super simple but oh-so-magical kids’ science experiment had my kiddos mesmerized and was a fun way to learn about capillary action.  Stock up on toothpicks because this trick will have little scientists begging you to do it again and again!

It’s the perfect compliment to our 30 Science Experiments!

Magic Rainbow Toothpick Star

Getting Ready

The prep for this kids’ science demo couldn’t be easier.  I quickly grabbed:

  • Toothpicks (we used colored ones but plain would work, too)
  • A plate
  • A dropper (a straw works, too)
  • Water

Making the Magic Star

To make the star, I took 5 toothpicks,(one of each color) and carefully bent them in half until they snapped but didn’t break apart.  It took me a few toothpicks before I got the hang of bending them in half without completely breaking them.

Magic Rainbow Toothpick Star

Once I had 5 bent toothpicks, I arranged them on the plate with the middles (the bent parts) of each touching to form a closed star shape.

Magic Rainbow Toothpick Star

Now we were ready for some kids’ science magic! Using a dropper, I slowly added a few drops of water to the center of the star and waited.


It only took a few seconds for the magic to happen and the star to open.  Both my kids’ jaws dropped and my littlest just had to climb up on the table for a closer look.


We repeated the kids’ science demo several more times since each of my kiddos just had to have a turn adding the magical water droplets.

My 6 year-old was pretty confident she knew the secret behind the magic.

“The water pushed the toothpicks apart when you dropped it in,” she explained.  She was on the right track… sort of.

The Science Behind the Magic

The toothpicks we used were made of dried wood.  When we bent the toothpicks in half, we stretched some parts of the wood fibers while compressing other parts inside the toothpick.

We placed all the bent parts of the toothpick together in the center of the star formation.  When we added the droplets of water to this bent part, the exposed dry wood fibers absorbed some of the water and became swollen.

As the wood swelled, it causes the toothpick to straighten itself.

As it straightened, the pointy ends of the toothpicks pushed against each other causing the star to open.

To get more specific, the water is absorbed into the wood fibers due to capillary action.  Capillaries are tiny hollow tubes within plants, like the trees that the toothpicks are made from.

Capillary action, the ability of a liquid to flow in narrow spaces against gravity, occurs in plants because water is attracted to the sides of the tiny straw-like capillaries (xylem).

As the water molecules move into the xylem, they pull additional water molecules with them because water molecules are “sticky.”  This process is called cohesion and occurs because water molecules are polar, they have a slight positive charge on one side and a negative charge on the other.

More Irresistible Kids’ Science

Continue the excitement with 30 of our favorite, kid-approved science experiments PLUS a no-prep journal for scientists to record their results!

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  1. I have selected this experiment to have the kids do at Vacation Bible School this week. Our theme is “Stellar” and it’s all about space and how Jesus is the light of the world! Praying it works each time so we don’t have any disappointments elementary kids!! Thanks for your post. Connie Rute in Milton PA

    1. It sounds like the rainbow star will be perfect for your theme, Connie! I hope the kids love it!
      Sarah // Playdough to Plato Team

  2. Do you have a brand of toothpicks you used? We tried this with our wood toothpicks and it didn’t work at all. My daughter was sad so I thought I’d see if there’s a brand you know works. Ours are wood ones just not colored.

    1. Hi Skye,
      I’m sorry to hear this didn’t work well for you! We did not have a specific brand that we used as the important part is just that they’re made of wood. I hope you’ll try it again!
      Sarah // The STEM Laboratory Team

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