5 Fun Christmas Math Riddles and Brain Teasers for Grades 1-8 These Christmas Math Activities are a great supplement to our super popular 12 Days of Christmas Math Challenges and 10 Free Christmas Math Activities for Your Kids. All of the math riddles, puzzles, and brain teasers below are from holiday versions of activities from our best-selling 101 Math Riddles, Puzzles, and Kids Ages 10+!