Here’s a fun science activity that demonstrate’s Newton’s 3rd Law of Motion, and it’s also a lot of fun! Use a straw and a balloon to make a spinning pinwheel.

The pinwheel works by inflating the balloon and then letting it go. Air rushes out of the balloon through the straw, which causes the pinwheel to spin. It’s a neat science toy! We didn’t think of this idea – I found it on Pinterest via this website.

To make one, you will need:

• Straw
• Pencil – with a good eraser
• Straight pin
• Tape – we used duct tape
• Balloon

Attach the balloon to the straw with duct tape. You want to create a nice tight seal.

Then attach the straw to the pencil with the straight pin. The instructions we read said to attach it at the balance point. Find the balance point by balancing the straw with the balloon attached on the end of your finger. Well, our balance point was in the middle of the duct tape, and we didn’t think that the pin would spin very well if we stuck it though the tape. We decided to place the pin just past the tape, and it worked great.

Blow up the balloon by blowing through the straw. It’s a little challenging, but my 13, 9, and 7 year olds were all able to do it.

Then let go, and watch the balloon spin! It spins faster as the balloon gets smaller.

This project demonstrates Newton’s third law of motion which says that for every action, there is an equal and opposite reaction. As air rushes out of the straw, it pushes the straw in the opposite direction.

Aidan pointed out that the pin is also exerting centripetal force on the straw, causing it to move in a circular motion.

Pretty neat, huh?

Need more science ideas? View our STEM (science, technology, engineering, and math) category here: STEM Activities

1. ##### Pamela Kim May 1, 2017

We learned about Newton’s 3rd Law of Motion in our Classical Conversations cycle this year. This was a fun Science activity to reinforce what we learned. Thanks Sarah for another one of your fabulous ideas!!

2. ##### Christine Towgood Mar 30, 2020

Thanks Sarah, you make science fun for all. Really needed at this time.