The average rate of change is the rate of change between the start and the finish, not simply at one point in time.Suppose you want to get to your friend's house in a hurry. You start running but then get out of breath and walk the rest of the way. The average rate of change in your distance from your home will be the total distance to your friend's house divided by the total time taken to get there. The instantaneous rate, when you are running, will be a measure of how much distance that you are covering per one moment of time then. This will be greater than the instantaneous rate when you are walking.