For a challenge, try this Pi Day sudoku puzzle. The rules are a little different from standard Sudoku, in part because the blocks are jigsaw pieces rather than and in part because the first 12 digits of ? are used instead of the standard
This pi mobile would be a great introduction to pi, the concept of irrational numbers or as part of a study of Albert Einstein, who was born on Pi Day! Students can color all parts of the mobile while learning facts about pi.