Garbage! Monster! Burp!

A monster at the bottom of a hill eats all of the garbage generated by the town on top of the hill. This provides two important benefits: The monster is happy with plenty to eat and the town stays nice and clean. Unfortunately, as the town grows, so does the amount of garbage the monster must consume. He gets bigger - and he starts burping. This is, as you can probably guess, a bit unsightly and stinky. In the end, the kids figure out how to solve the problem - despite the nasty mayor's doubts and objections.