Or paper helicopters. Whatever you call them- they are fun to make and even funner (is that even a word) to fly!
You need a piece of paper, scissors and a paperclip or some tape.
Cut the paper like in the video where the top piece is in half and the bottom is cut in thirds. Fold the bottom thirds towards the middle and tape or use a paperclip at the bottom to hold them together. On the top, fold the 2 blades in opposite directions so it looks like a helicopter blade. Now just toss it in the air.
Do they go faster it you add more weight to the bottom? What if the blades were bigger? Try different combinations to see what happens.