Good enough to eat!
A monster that eats children came to a school - they only ate certain numbered children in the register. They ate number 5 and number 29. They didn’t, however, eat numbers 6 or thirty. Why could that be?
We extended this question by adding other number they might or might not eat before coming up with rules to their selections. We then attempted to apply these rules to larger numbers and added another monster to see if we could determine who was safe or not!