Lower and Upper Sum of a Function
Here, you can see a function with its upper sum and lower sum on the interval [A,B.]
1) Drag the endpoints A and B of the interval with the mouse. What characteristics of the rectangles of the (a) lower sum, (b) upper sum do you see? 2) Now, change the number of rectangles n by moving the slider with the mouse. How does this affect the difference between lower and upper sum?