Spheres

To see how the surface area of a sphere is really 4πr², find a ball to wrap (a basketball works well). Cut some wrapping paper to fit the ball, and then lay the wrapping paper out flat and measure it to see whether the length is about the circumference of the ball and the width is about the diameter of the ball (a little less than a third of the circumference). It won't be exactly right, because of the extra you need to be able to tape it, but it should be pretty close.