"Move a book back and forth by blowing on it? Try it!
You will need:
Two long pieces of string or rope
Wooden clothes hanger
What to do: Loop two pieces of string around the book and knot them. Then tie the loose ends of the strings to the rod of the wooden hanger so the book swings freely. Blow on the book. Continue blowing on it every time it swings back toward you.
What happens: Even gentle blowing seems to make the book swing vigorously.
Why: It is not only a question of force, but also one of timing. Although you may not be blowing very hard, regular blowing at the right moment sends the book flying."
What happened when CKS tried it: It only works when you blow hard and fast. It was a little bit scary to use a big book because it might fall on the floor and make a big noise or land on your toes. When you try it, make sure to use a light, small book.
CKS rating: 3 stars - As good as an ice cream cone.