In this video, we will be using graphs to relate two quantities. Graphs are used here to measure rate of change over a certain period of time.
One example mentioned in the video is water in a bathtub. The graph’s starting point is always at x=0, and the y value on the graph represents the initial value. If the rate at which water is being added or drained from the tub is constant, then that rate of change will be represented by a straight line on the graph.