Paul Giganti runs some great math festivals in California, but I've wondered how we could help spread the good work he does. The SNAP Math Fairs have the kids running the math festival, while their parents wander around trying to solve the puzzles. Each kid is the expert on one puzzle, and can help visitors to their booth solve it if needed.
The website includes a puzzles page, a resource page with more puzzle ideas, guidelines for organizing your own SNAP (Student-centered, Non-competitive, All-inclusive, Problem-based) Math Fair, and lots more that looks useful. They make it look easy.
From the puzzles page:
Number wheelIn the figure on the left, numbers have been placed in the circles. For every pair of neighbouring numbers, the sum of the pair equals the sum of the opposite numbers.
The problem is to place the digits 1 through 6 into the circles using each number as few times as possible. In the picture on the left, we used the number 3 twice.
In each of the figures below the 1 and 5 are already in place. In each case, finish the puzzle by putting the numbers 2, 3, 4 and 6 in the proper places.
(This is a simpler version of Order the numbers from The Moscow Puzzles by Boris Kordemsky)
If your child is in school, this would be a good way to help move their math program in a kid-friendly direction.