Drops on a penny is a water cohesion activity is a fun STEM activity for school age children. Demonstrate water retention with this challenge for kids.

Drops on a Penny Supplies

• Pennies
• Eye Droppers
• A Bowl of Water
• Many, Many Towels    

Set Up Water cohesion Activity

Decide how many kiddos you want participating at a time. Place a bowl of water in the middle of the table. Set one penny and one eye dropper for each child around the bowl. If you need droppers I found a 20 pack of eye droppers cheap on amazon.

Ask each kiddo to guess how many drops of water they think they can get onto the face of the penny. The Challenge Have the youngins’ fill the eye dropper and carefully drop one drop at a time onto the penny. Ask them to count the drops as they go. Keep counting until the penny can no longer hold the water and rolls off the sides. Keep dialog going as the kids work. Ask questions like what do you see happening? how many drops did you get? Do you think you can make more water drops stay on the penny? Why do you think the water does not fall off the right away?

In my experience the kids love trying to beat their record, each kiddo must have done it 10 times! This water cohesion activity is easy to setup and run and is a hit with kids kindergarten through 6th grade!

What is Happening?

When the water drop hits another water drop they combine into a bigger drop. As the drop grows it creates a dome on the penny. This happens because the water molecules stick together creating the dome. The dome grows as more drops are added until the penny can not hold anymore and gravity pulls the water dome apart. Thus the need for many, many towels!