Overall, fun unique concept for your first game! The art was very fun and the vibe in general felt really stylized and a small thing, but I loved the planets haha.
It seems like the UI is smaller than intended? I think my biggest issue was this pretty much. It was a bit hard to read. It was kinda good for grading the student's papers since I didn't have to move my mouse much but everything felt a little small.
It also may have been nice to add a bit more information at the end like how many student's papers I graded so that instead of just the accuracy so that I could know how fast I went or try and beat my record from last time.