Calculus - Connecting How Fast with How Much
Calculus connects the rate of change of a quantity with the amount of the quantity. Imagine we have a water tank that we can fill or drain. The rate at which the tank is filled or drained is given in gallons per minute (gpm), and the amount of water is given in gallons. The fill rate can be changed by sliding any of the red "dots" to create a fill/drain rate "profile" over time.