My response:
Well, it sounds like you and your son have a good lawsuit against the School District, the Principle, and it's Administrators. Also, you both have a good lawsuit against the other child, and his father, for the medical damages, your son's pain and suffering, and punitive damages.
Remember, when you see your Personal Injury attorney with your son, that you must also file a "Claim for Damages" against the School District before a lawsuit can be commenced.
Good luck to you.
IAAL