Still apparently at least one bug in the system: if I play around with the same pizza for long enough, I can create a situation in which it's drawing secant lines across the pizza (not through the center). This has something to do with the blowtorch, a tool I added just this past week. It may also have something to do with the way the program keeps track of groups of slices.
-Improved playability (some things are difficult to click).
-Animation of fractions as they change (actually show fractions joining together, reducing, etc.)
-This is the biggest thing: A quiz that will challenge the user to solve fraction problems using the manipulative, and will make this a kind of puzzle game.