Advice- wording

Hi! I really need advice on how to proceed forward and wording on emails.

My son is in 4th grade and a full time wheelchair user. Inevitably every year some kid will come up behind him, grab his chair and start running/playing while pushing him against his will and will accidentally flip him in his chair. He has gotten really hurt from this before and every single year I start the school year by meeting the teaching and having a chat. Every year I talk about not allowing kids to push him. He doesnt need help, nor does he want it. This is always my #1 most emphasized point when we meet and even though kids still try, the teachers usually set a good standard for not allowing it and it minimizes the times it happens. Last year he was not flipped a single time all year long and the teacher did a really good job making it clear to the class that it is inappropriate to push him without isolating him from his peers and modeling correct ways to interact with a wheelchair user.

This year, however. He is getting flipped at least once a month. It happened again today and he said kids are constantly coming up and trying to play with him and pushing him on the playground and in the halls. It's hard because he's young and he sees it as fun sometimes and he hasn't learned to be as assertive and say no repeatedly if they don't stop. I have sent numerous emails to the teachers and it keeps happening. Please help me know what you would write to help explain how important it is that kids don't push him. I'm angry that this keeps happening and don't want to just be mad and it's clouding my words haha. I just don't understand why I have to sit here and convince the teacher of its importance for the 1,000th time this school year. Please give me ideas.