PI DAY ACTIVITY COLLABORATIVE POSTER WITH WRITING PROMPT. Math class collaboration for Pi Day is fun with this poster for your math teaching lessons. Teachers will receive 3 size options to use for this Pi Day writing activity poster. Albert Einstein appears to be very relaxed in his Pi Day shirt. It will bring cheer to any math, algebra, or geometry classroom. Use it in English language arts, science, and social studies, too! It's just fun! ($)