As a whole class reward system for my class, we put a ‘pin in the board’.
I made over an old cork noticeboard with a snazzy star design and marked the positions for 50 drawing pins. At the beginning of each rotation, the children choose their reward, e.g. movie afternoon, extra play, picnic lunch out, etc. This is put into the middle of the star on the board.
Every time the whole class does something special, they get a pin on the board. I have found that this works really well, and my class love to think of exciting new rewards.
The board sits on the side in my room, doesn’t get in the way, and the children can all see it to remind them to be good!