Bullying?

Cooper is having a hard time at school lately, well in particular it's just his Gym class.  He has asked me several times to pick him  up before PE starts.  That is so unlike the little guy.  He usually loves sports and being active, so I am trying to get to the root of what is going on.  He says there is one kid in particular that has been pushing him around  A LOT in gym.  I know of this kid, and have noticed the couple of times I have volunteered for activities that he is much rougher than the other kids.  Supposedly on Tuesday, he pushed  Cooper to get his spot and caused Coops to hit his lip against another's head, he ended up with a bloody lip.  For the entire PE class, Cooper was benched while this kid continued to create havoc.

This is the thing I can't seem to understand about little boys. What is horseplay and what is bullying?  Danny and I have talked about this several times.  You don't want your kid to be pushed around but you want him to be a gentlemen.  What is the line that you draw?  I know Cooper is very laid back and shy in certain situations, which I'm sure is the perfect situation for a bully to exploit.  Danny told him last night if someone pushes you, you push back and then Mom and Dad will take care of repercussions. (Unless it's a girl, of course).  I hope we can figure out exactly what is going on in school.  I don't want to be a helicopter mommy but I do want to make sure my child is getting the best of his education, we are paying enough $$ for it.

Let's hope we can get Cooper back on track.