I tried to pick a topic that kids might see on a normal basis. We have six ceiling fans in our house. At five blades each, how many blades is that?

Do you have fans in your house? Here's some math (especially geometry) you can discuss and do with fans...

Find a fan to look at that can turn on.

- Notice the basic parts of the fan (the center (which may or may not have a light), the blades, the speed setting).
- When the fan is turned on it spins (in a circle) around the center (the central axis).
- Each fan blade will rotate 360° to make a circle around the center (Explain that degrees are measurements of angles.)
- Can you find the degrees between your fan blades?
- There is symmetry here, but not mirror symmetry (also known as bilateral symmetry), it's called "radial symmetry" (also known as rotational symmetry) and you'll notice it all around nature (flowers, starfish, etc.) and machinery (car engines and computers have fans) Can you find more?
- Radial symmetry is around a central axis--so imagine a straight line going from your floor to the ceiling (if you're looking at a ceiling fan) and the blades all have to be an equal distance apart from one another or else the fan won't be balanced.
- If you put a piece of colored tape on one of the fan blades you can more easily count the rotations per minutes (RPM) at the different settings of low, medium, and high.

You could also talk and show things about electricity, the angles of the blades being at an angle to optimize ease of spinning, and easier or harder things.

Can you find math with FANS?