Students in a circle, count from 1 to 21 in order. If you say one number, play passes to the next person. If you say two numbers play changes direction. If you say three numbers then it skips the next person.
The person who says 21 is
eliminated or... has to change one number (between 1 and 21) into a word or sentence for the
next round to make it a bit harder.
And so on.