Use the sliders to rotate the top circle clockwise, increase/decrease the height of the rectangle, and increase/decrease the radius of both circles.

How does the circumference of the circle compare to the length of the rectangle?
How does the area of each circle change as the radius changes?
How does the area of the rectangle change as the radius changes?
How does the area of the rectangle change as the height changes?
If this were a cylinder with a top and bottom, what would the total surface area of the cylinder be equal to?