20 or 30 ago, I would've said this was a good book for junior high kids. Now it's probably good for 4th-6th graders! It shows all kinds of useless, but fun and interesting, tricks: how to look at your teacher and get his head to disappear, how to look at your outstretched arms and one will be shorter than the other, a topology trick of cutting a 3 x 5 file card in a certain way so you can crawl through the hole you make!, why girls can pick up chairs but boys can't, etc. etc. The book tells of 30 useless skills accompanied by pictures and the reasoning why each trick works. Neat stuff!