This morning before class I was picking on one of my students for having her organic chemistry textbook out on her desk. I believe I said something along the lines of 'how dare you contaminate my classroom with that!' She explained how she had an exam today and I let it drop. That is until later in the class when I was teaching about chelates. I had a sudden inspiration. I asked the student to pick up her organic book with one hand. I then warned her that I was going to smack the book. I did and she dropped it. Based on the size of most organic textbooks, I believe that very few people would be able to hold on to one with one hand while it is being smacked. I then handed her back the book and asked her to hold it with two hands while I smacked it. Sure enough, she was able to maintain her grasp of the book. I think this rather simple deomonstration did a surprisingly good job of driving home the point.