In my opinion, I do not think the school is liable if it was your son that broke his arm by just throwing a ball ( he could have had a hairline fracture or other issue that the school was unaware of, or just threw the ball too hard - accidents happen ). Would be different if another student had tackled him and caused his arm to be broken, then you could ask the Dept of Education to pay costs
There's three elements that must be proven in a negligence case:
- Was there a duty of care owed?
- Was that duty breached?
- Did it result in harm?
If it's reasonably foreseeable that an injury would result from the respondent's act or omission, then yes, a duty of care would be owed.
Is it reasonably foreseeable that a child would break his arm from participating in physical education? If they were doing mountain climbing or snowboarding, sure, but they were throwing balls, so probably not, but let's say it is.
Did the school breach its duty of care? Probably not - it would have to oust physical education from its curriculum to reduce the risk entirely, which is an unreasonable expectation.
I think a claim for negligence here would fail.