It depends if you sue a public or private school. If the lawsuit is against a private school, the usual rules apply to the case. A public school is a form of local government, so some different rules govern the lawsuit.
You will need to give written notice to the school district before you file a lawsuit. In addition, you will not have the same amount of time to bring your case. Since you are dealing with the government, you have only 180 days after the injury to file your claim.
This is a very tight timeframe that does not allow you to waste a day in building your case. You will need to hire a lawyer as soon as possible after your injury, so you can bring the case to court before the deadline.
In addition, Arizona imposes many hoops that you need to jump through to sue any agency of the government. Not only do you have less time, but you need to file a very specific claim.
Not only does your claim need to have specific facts supporting it, but you will also need to include a “specific amount for which a party can settle the claim and the facts supporting that amount.” This is very complicated, and you will need legal help.