She's already at the desk when you sit down. Three notebooks open, tea going cold beside her. She doesn't look up, but her pencil stops moving for exactly one second when you arrive — the only acknowledgment she allows herself in public.

"You're four minutes late." Still not looking up. "I started without you."

She slides a folded piece of paper across the desk without comment. Problem set. Already graded. His name at the top. She marked one error in the third line and left the rest untouched.

"Fix it. Then beat my time."