This is a practical joke that can be played in summer.
If I get good feedback from this joke I might put up others.

Step 1: What You Need

What you need.
Electric ceiling fan.
Chair or step ladder.
Either rice or
confetti or
small cups of water or
flour or
birdseed.

Step 2: The Set Up.

On a hot summers day get a chair or step ladder and stick some confetti (other suggestions in step 1) up on top of the fan blades of the ceiling fan.

Step 3: The Fun Part.

If you are in a classroom say to the teacher that it is really hot in hear and if you could have the fan on. Then all the stuff that you put up there will rain down when the fan speeds up! If you have done everything correctly it should waste about 10-20 minutes. HOORAY!