What better way to show your Valentine you care, than to make them a flexagon! You can print out this cool Valentine tri-tetraflexagon card, featuring teddy bears, at Aunt Annie’s Crafts. Or, you can choose the plain frame template and add your own pictures. But, if you want to make them for an entire class, make sure you start now! It takes some time to print, cut out, and fold. (My son is making these, and he has made enough for about a third of his class so far.)
If this seems like too much work, there are tons of cute math-themed pictures on the internet you can turn into Valentines. Last year, we found cute a Sierpinski Valentine.