The following descriptive video corresponds with Figure 7 in Network Sense: Methods for Visualizing a Discipline by Derek Mueller. What you see in the viewport is a Google Motion Chart. You can adjust the settings for the chart, choosing the axes from the left-hand dropdown menu, which right now shows Reference per 1000 words, and the horizontal dropdown menu, the axis shows there percentage of articles. To model a gradual turn, the word assessment has been preselected. Trails is turned on. Upon clicking the gray playhead, what you'll see here is a year by year indication of the relative frequencies of this term as it has appeared in the journal College Composition and Communication. As the animation advances, bubbles change locations, rising and falling to show the changing positions of this term over twenty-five years.