Approximation of area under a curve

Author:
Aibhín
Topic:
Area
This shows how we can use upper and lower sums to approximate the area under the curve. Use the slider n to change the number of rectangles used to calculate the upper and lower sums.
What happens when n is (a) small, (b) large? Can you think of any way that we can make our approximation of the area under the curve more accurate?