ecosystem.rkt

It feels good not having anymore tests for the next few weeks! Although I still have a few assignments to do; one of which I'm having some difficulty completing at the moment. For CSC104, we have to make an "ecosystem" in Dr. Racket. You have a picture of a fox and a mouse, and over time the pictures scale according to one another. So, a large fox picture means there are very few mice and thus a small mouse picture, and vice-versa. But my ecosystem is not very ecosystem-like. Instead of continuously growing and shrinking in size, my ecosystem only "ticks" once. Anyone else having this problem? I'm not sure how to fix this...