The Penny Experiment
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Penny Experiment with Water Drops


A penny experiment that demonstrates how water tension works and water can hold together in a dome shape – a super simple science experiment for kids!

Penny Experiment with Water Drops

Drop water on a penny and it just runs over the side, right?

Maybe not…

Maia was excited to show us a penny experiment she learned at school that demonstrated how water can hold together in a dome shape. This super simple science experiment requires only a penny, some water, and a dropper.

The Penny Experiment in Action

Penny Experiment with Water Drops 1

She showed us how we could carefully squeeze a drop of water at a time onto the top of the penny…

Penny Experiment with Water Drops 4

…and the droplets would combine to form a bubble of water.

Penny Experiment with Water Drops

Maia thought it looked a little like a snow globe (one of her favorite things).

Penny Experiment with Water Drops 3

We each tried the penny experiment to see how many drops of water it would take before it reached its limit. Because once it did, the water bubble burst and flowed over the edge of the penny.

Penny Experiment with Drops of Water

Pretty cool, eh? We all had fun with this one. I think it’s definitely worth keeping it in mind for a rainy afternoon. Or just when you need a quick and easy activity for the kiddos.

By the way, if you want the technical explanation for why this works and what’s going on with the water, check out Steve Spangler Science.

3 More Favorite Simple Science Experiments for Kids

  1. The Rainbow Milk Science Experiment
  2. Make Painted Daisies
  3. Make a Baking Soda Volcano

P.S. Want even more science? Here’s my collection of The Best Kids Science Experiments to Try at Home.

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Penny Experiment with Water Drops -- Kids love to see how many drops they can fit on a penny! #kidsactivities #scienceforkids #scienceexperiments #stem #education


  • Reply
    Kate - An Everyday Story
    October 15, 2013 at 6:17 pm

    So simple but so fascinating :)

  • Reply
    October 16, 2013 at 8:49 am

    Yay for the link at the end. I was just going to comment that this is a perfect time to talk about cohesion and even hydrogen bonding. The water sticks together because the hydrogens keep high-fiving each other (as opposed to each water molecule itself, where each H is holding hands with oxygen). Their bond is really brief, but all the H keep making that bond, so the water is “sticky.”

  • Reply
    October 17, 2013 at 12:56 am

    Neat! I actually have a question about your playclay monsters from a couple days back. After you’ve enjoyed your monsters for a few days/weeks/etc do you remove the poke-ins for use another time? Or do you toss it all? I want to try this with my three this weekend!

  • Reply
    Jean Van't Hul
    October 17, 2013 at 8:48 am


  • Reply
    Jean Van't Hul
    October 17, 2013 at 8:50 am

    Thanks for that description, Leah! I love the idea of the hydrogens high-fiving each other! I’ll borrow your words to describe it to my daughters…

  • Reply
    Jean Van't Hul
    October 17, 2013 at 8:55 am

    Hi Tara – I remove the poke-ins later the same day usually and put the playdough back in its storage bag/container. It’ll dry out otherwise. My kids just know that when we make things with playdough, we enjoy them briefly, then the playdough gets smushed back into a ball and they can make something new next time.
    If you wanted to, though, you could do the same sort of monster project with poke-ins but use air dry clay or regular clay and then just let it air dry and keep it as is. Now that I’m writing this, I want to try it again with air dry clay!

  • Reply
    October 17, 2013 at 9:48 pm

    I teach science :-) I used to teach homeschool, and I’d have kids ages 4-14 that had to get the same concepts. I love finding new ways to explain science to kids. I can’t wait to have my own children so that I can do science experiments and the kind of art stuff you do.

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