Just a quick Pi Day pointer, math teachers: be sure to remind students that Pi is a constant rather than a variable. The misconception that it’s a variable comes in part from the fact that we often express circumference and area in terms of Pi. I especially notice confusion when students work with the formula, Circumference = 2πr (there’s something about multiplying the two outer factors, r and 2, and leaving π alone that gives students the impression that π is a variable).
Happy Pi Day!

Image by Toponium, provided by Dreamstime license