First, let's talk about running in circles. It seems to be a wonderful past time of young children. But it is also a really amazing way for children to understand their bodies in the world. Consider this video of my daughter running in circles:
She is not just making a circle with the path of her feet. Her body is leaving the path of the circumference of a cylinder behind her. Her little brain must be lighting up neurons all over the place.
My son's version of circular body motion is also popular among young children - especially autistic children - spinning. Our "Johnny Jump Up" should have been called a "Sammy Spinner." He would spend his time spinning himself on his toes as much as he did jumping and swinging. Not only was his body and brain making connections about the world, he was learning circular motion.
In fact, open-armed twirling might be the perfect Pi Day activity because the fully extended arms are your child's circle's diameter, the trace of his or her fingers are the circumference of the circle, and the relationship between them is Pi. So go ahead, let your young children run in circles or spin in circles on Pi Day. Those big movements might be the way to celebrate such a special number!