At my children's school, each class teacher picks a child who is"Star of the Week". The names are announced in the weekly newsletter. In assembly on a Friday the children all go up to the front and are given a chocolate medal. And the end of each half term all the chosen kids have a tea party (cake and juice) with the head teacher.
The same children seem to get picked all the time. I know this because I have 3 kids at the same school. One seems to get picked every 3 or 4 weeks, one has been picked 4 times this school year and one has only been picked the once.
I personally think each child should get picked once and then repeat throughout the year.
My child who has only been picked once gets upset every time one of his siblings gets picked.
How does it work at your kids schools?