My son came home from school after a weekend away with carpet burn on his knees he said it had just happend at school but they were dry and not pink c?

See below: He may resent your inquiring about something that may be more embarrassing to him. Give him some time and perhaps he will reveal how he got it. Pick and choose your battles. I doubt it is anything that is dangerous if he is otherwise healthy and well.

Burns: I'm not sure what the question is here. However, the color changes to which you refer would indicate that any skin injury that exists involves far more than the superficial skin. Plus, the darkness indicates that the abrasion injury is greater than 24 hours old. I would be concerned about the child's activities in which he can sustain an injury like this.