DIY Windmill: A Simple STEM Activity
Updated: Aug 30
What happens when moving air meets a set of spinning blades? Today we're going to find out!
A simple paper windmill is an easy, hands-on way to explore wind, motion, energy, and design. With just a few basic materials, kids can build their own windmill, test it, make changes, and see how those changes affect the way it spins.
You don't need a complicated lesson plan. Just build, test, wonder, and try again!
What You'll Need
A square piece of paper
Scissors
A pencil
A pushpin
A straw or small stick
A fan or a breezy outdoor space for testing
Let's Build a Windmill
Start with a square
If you're using regular paper, cut it into a square. You can use any size you'd like, but a smaller square will make a smaller windmill, and a larger square will make a larger one.
Cut toward the center
Draw diagonal lines from each corner toward the opposite corner if you'd like a guide.
Starting at each corner, cut toward the center of the paper. Stop before you reach the middle. You want to leave the center connected so the windmill stays together.
You'll now have four sections that can become your blades.
Fold the corners
Take alternating corners and carefully fold them toward the center.
Don't crease the paper too tightly. The goal is to create blades that angle slightly so they can catch moving air.
Secure the windmill
Push the pin through the folded corners and the center of the windmill. Make sure the blades aren't pressed so tightly together that they can't move. The windmill needs to be able to spin freely.
A quick safety note: Pushpins are sharp, so an adult should help with this part, especially with younger children.
Add your handle
Attach the windmill to a pencil, straw, or small stick. Leave enough room for the windmill to spin without rubbing against the handle.
Test it!
Take your windmill outside and hold it where you can feel the breeze. No wind? That's okay! Use a fan instead.
What happens?
Does it spin?
Does it spin slowly or quickly?
What happens when the wind gets stronger?
Now It's Time to Experiment
Once you've built your first windmill, don't stop there! Change one thing at a time and see what happens.
Try:
Making a larger or smaller windmill.
Making the blades wider or narrower.
Changing the angle of the blades.
Using different types of paper.
Making the blades longer or shorter.
Testing it in different amounts of wind.
Ask your child to predict what will happen before testing it. For example: “I think the larger blades will spin faster because they can catch more air.”
Then test the idea!
You can even keep track of your results with a simple chart:
What did we change? → What did we predict? → What actually happened?
This turns a simple craft into an engineering experiment.
What's Happening?
Wind is simply moving air. When the moving air pushes against the angled blades of the windmill, it causes the blades to move. The windmill takes some of the energy from the moving air and changes it into motion.
This same basic idea is used in much larger wind turbines. Instead of paper blades, wind turbines have large blades designed to capture energy from the wind and help generate electricity.
Think About It
After testing your windmill, ask:
What made your windmill spin?
What happened when you changed the blades?
Did a stronger wind make a difference?
Which design worked best?
Why do you think that design worked better?
Where have you seen wind doing work in the real world?
You can even challenge your child to design a better windmill. Give them a goal, perhaps to make one that spins for the longest amount of time or spins the fastest and let them figure out how to change their design.
Learning Doesn't Have to Be Complicated
This is one of those STEM activities that can start with a piece of paper and turn into a much bigger conversation about energy, forces, motion, engineering, and renewable energy.
Build it. Test it. Change it. Try again.
Observe → Wonder → Explore → Discover
Sometimes the simplest activities give us the most opportunities to ask questions.
Comments