My dear buddy Paul has a post on his blog containing a number of images of the works of Avi Ornstein.
I particularly like this one, but they're all great!
In my search to find more of Ornstein's works I came across a page, dated 1991, by a German high school chemistry teacher, explaining how he runs the first day with each class.
It's all about teaching the students to concentrate and listen carefully. One of the things he asks them to do is "Say 'ten' ten times". Excellent!