Robomatic, I use them for the same reason you do - to quell hyperactive riots in classes I teach. It doesn't matter what age group or what interests or levels of ability, these problems can quiet a room in about 10 seconds. Except for the groans, of course, of the "oh, no, not these again" variety. But even the groaners join in. It does work exceptionally well as yes/no questioning in a group and I justify using them in my workplace communication classes as practice in the use of effective questioning techniques, but really it is a filler for the last 10 minutes or a rescue package for a harassed teacher - me!

My book is by Paul Sloane, called The Lateral Logician. It has maybe 300-400 problems. There is a website with many of his problems, with clues and answers.

The way to do it here is to pose the problem, ask that anyone who knows the answer stays out of the exercise, and then everyone else asks yes/no questions from the person who posed the problem and waits for the answers. Eventually enough info is compiled to start seeing possible solutions.

If you want to try it out, one of my favourites is:

The music stopped and she died.