mabey you can do it by grade level (ei elemetary, middle, high, and phisics/caculus 7/ whatever you do in collage)
or do
addtion, subtraction, mutiplcation, division, fractions, order of operations, equations/algebra, graphing, gometry etc.
mabey do subsets in each grade level, so that a middle school student who (for exaple) exceled at probabillity can help a third grader without being to intimadated to answer with questions like "What is the subset of 74 squared times the speed of light in a vaccum divded be the weight of a humming birds eyeball in scientific notation? please show all graphs."
mabey one for riddles/ brain teasers?
sorry for spelling mistakes i'm tired