Since pi approximately equals 3.14, March 14 [3-14] was chosen as the date to celebrate pi in countries that use the month/date format. Pi Day was founded by now-retired physicist Larry Shaw 1988 at the San Francisco Exploratorium. Nowadays, the holiday is celebrated by eating different kinds of pie, and by discussing the relevance of pi.
I'm wondering what those discussions sound like. We haven't gotten that far at my kitchen table, I'm afraid. But I have always had a mad fondness for pi, as the refuge of both the "irrational" and the circumference of a circle. And I wish I'd had some math teachers who talked more about the ideas in math – my kids have been lucky that way. (Thank you, Mr. Berzins!)