How to pretend to be sick and ask for leave

You can tell the teacher, (that your parents promised you? Who is sick today? My mother took me to see her this afternoon. Or the most awesome way is to put a thermos bottle on your forehead all the time, and then say to the teacher, "Teacher, I have a headache (pay attention, my movements should be very painful, my face should be expressionless and pretend to be sleepy)" (the teacher will definitely touch your forehead).