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How Many Drops Of Water Can You Put On A Penny?


Make teaching surface tension fun and easy with our STEM Challenge!

The challenge is to find out how many drops of water you can put on a penny. Ready to make learning fun? Read on!

This challenge will take around thirty minutes to complete.

What you need per student...

What you need to do...
  • Hand out the required materials to each student.
  • Start by making sure students have a general understanding of what surface tension is...
  • According to Kids.Net.Au, surface tension is a force present within the surface layer of a liquid that causes the layer to behave as an elastic sheet.
  • Example: It is the force that supports insects that walk on water.
  • Have students define surface tension on their creator sheet.
  • Tell students that the challenge for today is to find out how many drops of water they can put onto a penny. Have students predict and write on their creator sheet how many drops of water they can put on their penny.
  • Using the dropper, have students put a drop of water in the center of the penny.
  • Have them observe what happens and continue to add water one drop at a time.
  • Make sure that they keep count because the challenge is to see how many drops of water they can put on a penny!
  • Have students draw on their creator sheet what they are observing.
  • Let students continue to drop water onto their pennies until the water spills over the coin.
  • As students finish their challenge have them assess what happened and write how many drops of water they fit on their penny.
  • Once students have all completed the challenge ask students to share how many drops of water they could put onto their penny.
  • To extend the challenge even further, you can ask students why they think they could only put so many drops of water onto the penny before it spilled over.
  • Have them put their answers on the final thoughts section of their creator sheet.
  • Answer: Continuing to add water drops makes the surface tension weaker. When the water spills over it is because the surface tension is not strong enough to counter the gravitational pull on the water.

We would love to see you try this STEM Challenge. Share your results with us through social media!

Happy Making,

Maker Maven

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