A referee in a high school wrestling match turns his back to adjust some mats. While he is distracted, one competitor uses an illegal hold on the other, severing his spine and rendering him paralyzed below the neck.
The school argued that the referee was an independent contractor, and that the student had assumed the risk. The court ruled in favor of the student, holding that “one is never held to ‘assume the risk’ of another’s negligence or incompetence.” 
Later the Washington Supreme Court held in a different case that “exculpatory releases from any future school district negligence are invalid because they violate public policy.” 
Having said all this, an injured student would still have to prove negligence on the part of the school. It is not the rule that schools are strictly liable for all injuries to students.
As an aside, the father of the young man who was paralyzed in the wrestling match was apparently a pillar of the local Anacortes community. He was recognized by the local hospital for his contributions and there is a scholarship in his name. (We took no part in the case.)
 Carabba v. Anacortes, 72 Wn.2d 939 at 958 (1967).
 Wagenblast v. Odessa School District, 110 Wn.2d 845 (1988).
 See https://www.anacortesschoolsfoundation.org/our-programs/scholarships-66/83-island-hospital-scholarship-in-memory-of-sa-john-carabba.html and https://www.goskagit.com/news/island-hospital-community-award-goes-to-carabba/article_d18b761d-9f2b-57cc-bef7-9608dcd2bc24.html .