Tell your Pediatrician, to write a note, with instructions.
Then give that to the school.
So... is he sensitive to 'light'.... or has light colored sensitive skin????
If he is sensitive to light... then he shouldn't be out in the sun???
Also, my son does not have sensitive skin... but, whenever he is playing or running around... his cheeks gets very red. That is just the way he is. It comes from my Husband's side of the family. And he sweats a lot. Boys. They sweat a lot.
From here on out, being he is in Preschool... every year and at every grade level, you will need to apprise the Teacher/his school about this.
Each grade level, each Teacher, has a different routine in class.
The thing is, the Teachers won't know about this, unless you tell them. Or bring in a Doctor's note.
And I don't know what you mean by boo-boo's on his face?
What about boo-boo's anywhere else on his body? Little boys often get bumps or scrapes on their legs, from playing. Is your son's skin... sensitive all over, or just his face?