robomatic,

I found that even if the class was busting to get out of there not one of them would leave until the puzzle was solved. It's their niggly nature, these puzzles, they get under people's skin, like an earworm - that small part of a tune that keeps playing over and over in your head and nothing seems to get rid of it.

I bought my book on special for $2. The amount of stress-free teaching it has provided for me and the amount of fun and entertainment it has given my students - many of them young, active blokes beginning their trades course who can always think of something better to do than sitting in a classroom - I could have paid $2000 for it and still thought it was a great investment.

Try this:
One of Paul Sloane's Wally Tests

and please don't cheat and look up the answers.

   1. If a ton of coal costs $30 and a ton of coke costs $25, what will a ton of firewood come to?
   2. Removing an appendix is called an appendectomy, removing tonsils is called a tonsillectomy. What is it called when they remove a growth from your head?
   3. Why are U.S. soldiers forbidden to carry rifles any longer?
   4. What three things that you can eat can never have for breakfast?
   5. If a farmer raises wheat in dry weather, what does he raise in wet weather?
   6. What would you call a person who did not have all his fingers on one hand?
   7. Which is greater: six dozen dozen or half a dozen dozen?
   8. What is the best way to get down from a camel?
   9. How could a man be severely injured being hit by some tomatoes?
10. Why do Chinese men eat more rice than Japanese men?

(Reprinted from Great Lateral Thinking Puzzles)