my son got seriously hurt on the play ground at school what legal rights do i have? My son has permanent damage to his leg.

You need to file a Tort Claim Notice within 90 days of the event happening.  This Notice is essential to preserving your rights to bring the action.  If your son is a minor, you can also wait until he is 18 and file the notice and bring the litigation at that point. You will most likely need to retain a lawyer to help you sue the school district as to the injury, whether cause by negligence or however it occurred.