Learning Something New Everyday

Here at Mathnasium our guiding principle is to teach math in a way that makes sense to kids. Yesterday I realized how true that is while working with one of our students. Her topic was surface area of a sphere, she is a geometry student. I asked if she knows/remembers the formula, there are so many formulas to remember in geometry after all. After some hesitation she was able to recollect. I will be honest with you , I didn't remember it. By the way the formula is 4Pir². Not very complicated but again, there are so many formulas in Geometry. So, here is what I learned yesterday. Way back in the day when Greece was the center of civilization, and people had time on their hands, one Greek was able to figure out that if you fit a sphere inside a cylinder that has the same height as the diameter of the sphere, the surface area of the sphere is equal to the lateral surface area of the cylinder. If you unfold a cylinder it looks like a rectangle with two circles for the top and the bottom, So the area of the rectangle is the area of the sphere and that is 4PIr². Now, that is something I would always remember and even if I forget the formula I know how to get to it. And that is how we make things interesting for our students and make them like math.