An improvement from your other cartoons in many different ways.
The character design is very simplistic, though since this is a series that's already in its fourth season, I realize this cannot be fixed. Lubch looks different in this episode, especially the top part. It looks like you kept trying to re-draw it but eventually you gave up (kind of like when I kept trying to draw Joe's head.)
I liked the short pieces of music that accompanied each scene. They were simple but they fit the scene well.
Thaud asking "Why should I?" so many times would've been okay if you cut out the "Why should I?" after Lubch said he's jealous. (Also I like how he flat out admitted he's jealous.)
I like the "Stay Mad!" sign on the board. It's much better than something like "No fun allowed." By the way for future reference, try to avoid having characters impose rules like "No studying allowed" or "No fun allowed." Instead of having Lubch say "No fun allowed," have him make them all do something that wouldn't be fun anyway. Instead of him saying, "No studying allowed," have him give them a test on something they've never learned, that way studying would be useless anyway.
"Out of all the dumb luck" is an awkward line and "Out of all the bad luck" would be a better one. "Just find out the fact that you can get your own" is a VERY awkward line and "You do realize you can get your own?" is a better one.
Also I like how when he says "lame students" there is a balance of sad students and angry students.
The explosion sprite at the end works for most situations but not for this one. That explosion only works for large explosions that take up most of the frame. Otherwise, it looks awkward and unfitting.