Okay, several things that I wish this game had:
1. More difficulty in solving the actual problems.
Okay, provided that you actually made a working game, this alone is insufficient. The problems are really easy and predictable. It can't keep the attention span of anyone for long, and people who like slower things are also the type that has potential in reading a law textbook.
Therefore, in either situation, the difficulty needs to be both as hard as a law textbook or as fast-paced as a first person shooter, or a mix between the two. Games that were slow-paced but rated highly tried their hardest to engage the mind. One example is ir/rational. Most people aren't used to working with logical statements and arguments but that's what made it fun.
2. More control over what the player's actions cause.
When playing this game the cannon moves slowly and I feel like I have no control over what it fires at. That doesn't feel nice, and gets somewhat frustrating.
That being said, the animations are pretty. It would have been a better use of assets to make a movie out of this instead of a math game, but obviously you intended to make the focus around math.
I'm sorry, it's just a bit weak for me to give much more than 2 stars.