"Thank you. And - thank you for the knife. I appreciate that a lot." 

Marian smiles at him, and then goes back into the infirmary to look for anything vaguely usable as paper, to make a sign. (She is also going to poke LITERALLY EVERY OBJECT with her ivory knife before touching it; she's incredibly twitchy.) 

She has a lot of pens on her - tonight was one of those nights when she was finding them everywhere and putting them in her pockets on instinct - and she has a roll of medical tape as usual. She ends up sacrificing the paper wrapping for another square of gauze, in order to make a SIGN on the DOOR to helpfully inform students that there is now a school nurse who would be happy to do check-ups on them.

And then maybe she'll go try to figure out the creepy void wall?