Someone significant (spouse, child, significant other, neighbor, etc.) in your life informs you that you teach math. You get dropped off at your school (place of work) and are led to your classroom. Your principal can't find a substitute and your colleagues run to the photocopier to make you some busy-work handouts. You can't remember any mathematics and your students are 10 minutes away from entering your room, oblivious to all of this.
You look down and see this on your desk.
What do you do?