Good Afternoon Maurice (Or Good Morning/Evening depending on where you are)
You have committed two cardinal sins straight away in this short.
1) Dialogue immediately following a slugline - This is always a no. Screenplays are meant to be visual, what are we looking at? Yeah, your slug tells us we are in a classroom, but who's there? set the tone and mood with the visuals.
2) Character not introduced BEFORE they have dialogue - You need to introduce them first, otherwise, I (or a producer/director/whoever) has absolutely no idea what we are looking at.
Now that is out of the way, the story:
I like it. it has a clear theme, the protag and antag both follow their own arcs, good conflict and pacing. Looks to be easy to film as well.
With that being said, this is a good story told badly. The dialogue is very on the nose, unnatural, try speaking the parts with a friend and you will see what I mean. Even when he is talking to himself, it would be weird to hear.
The bully revealing his emotions was a bit out of the blue as well, he just kind of yelled it at him. it needs to be earned, the two need to connect on a more emotional level.
Read some scripts, bad ones and good ones, read the reviews of those scripts. It's a really good way to learn.
Best of luck to you