March 14 is “Pi Day”, according to fans of the number, because the date can also be written as the number pi rounded down to two decimals: 3.14
The Exploratorium in San Francisco has been celebrating the holiday since 1988, and kicks off at 1.59 PM (3.14159…) by “(circumambulating) the pi shrine 3.14 times while singing happy birthday to Albert Einstein”. That’s right, it’s also Albert Einstein’s 127th birthday today.
The mathforum website offers tips for teachers to celebrate pi day in the classroom. Most of them involve maths, obviously, but there are also suggestions to teach about the history of pi.
Another favourite activity is to celebrate pi day by eating pie! While a round pie appears to be very appropriate (after all, the circumference of a round pie is “pie” times the diameter) some people actually prefer a square pie on pi day. Why square? Well, isn’t it obvious: the equation for the surface area of a circle clearly says Pi*r2, or “Pie are square”!