Not a bad game. There isn't a whole lot to it, but it is solid and functional (I didn't encounter a single glitch while playing the game normally, good job).
I think the game is a little too easy. Except for the last three levels I had absolutely zero problem getting all of the coins while beating the levels for the first time. It wasn't until about level 15 that I learned that you could actually be in the enemies' line of sight ( I assumed it was an insta-kill like the first Classroom game), and wasn't until the last three levels that I didn't clear it on the first go.
Speaking of the line of sight, I think the amount of time you can spend in their (except for the bully) is a little too generous. The fact that I am able to dive in, grab the coin, and dip out all while the enemy is staring at me makes getting some of the coins that were set up to be a challenge to just be trivial. All while without even using the airplane.
Then there is the paper airplane. It's way too good. Even though the Nerds aren't much of a threat ever, the fact that you can stun, pick up the airplane and continue using it makes almost every level way too easy. The airplane should simply not be re-useable (you could have the tip be crumbled to signify that it can't be used again), and even then it would still be too strong. Like with the Bully, you cant recover the airplane if you use it on the Bully, not like you would need to. The Bully was a welcomed enemy, but with the fact that I can stun him in on position forever makes him more like a small wall that isn't a threat. What would have been better is that it stuns the bully for only for a little bit (like maybe 5-7 seconds[similar to the nerd]) so that the player can use the airplane strategically and with timing with the other enemies so they can dash and grab the coin, that would have been more enjoyable than just stunlocking the Bully.
I like the paper airplane, it's a nice concept for the gameplay. It just makes a fairly easy game even easier.
So overall for difficulty, I feel like two things would be a good change; make all enemies' line of sight's detection meter go up significantly faster (or even just make it an insta-kill) , and make the paper airplane an one-use-per-level kind of thing (maybe even some kind of powerup they have to grab).
Animation-wise. It is fine. I don't like how the enemies just snap in angles instead of smoothly turning around ( the same for the line of sight, which could have amped the difficulty a little more). But my actual complaint goes into the main character's walk cycle. By itself, it is fine, however, do you see how it is when he walks up, down, left and right? And then see how he walks in all of the diagonal directions. His diagonal walking looks like it would be a lot faster than his normal direction walking. His diagonal walking animation looks like running, while the up/down/left/right walking animation looks like he is just casually walking. It would be good to fix it to have all eight animations to be consistent in the appearance of speed, as it is currently jarring.
Art style is fine. It's appealing to look at, but that's as far as it gets.
The controls are alright, but a little clumsy-feeling when colliding with any object.
The audio is fine. Good choice of music, since I didn't get tired of hearing it by the end of the game, and I appreciate the option of muting it.
All in all, it is a functional game with an enjoyable concept. Zero story, but that is fine. No obvious glitches. Simply a good example of an average flash game, perfectly deserving 3 stars. It was enjoyable. Just kinda too easy, could use some more levels, and could use some general polish to make the game feel and look better.