The first display discussed is shown in Figure 6-6. One of the students, Will, and his teammate presented this graph on large, easelsized graph paper. As the figure shows, the authors first developed a scale (along the left side of the graph) to include all the observed heights of the plants. Then they simply drew lines to that scale, representing the height of each plant, ordered from the shortest to the tallest. As the class considered this display, Will tried to explain how this graph could be used to answer Question 1: “What is a typical height on Day 19?”

Will: “The tops of the lines represent height, and you have to see which lines stop and go along on one level. It’s … it’s the same number.” [He points toward a space in the middle of the graph where all the lines appear to be about the same height.]


Mr. Rohling: “So you’re looking for a flat line to tell you what typical is?”


Will: “Yes, then you can tell how many of those there are.”


Mr. Rohling: “What about Question 2: How spread out are the plants on Day 19?”


Will: “You can look at the graph and see that it starts low down here on the left and goes up on the right.“


Mr. Rohling: “If the data weren’t spread out, what would it look like?”


Will: “One flat horizontal line.”

This exchange shows that Will understood that “plateaus” on the graph denote clumps in the data. However, he went on to admit that the graph was display, like the display previously discussed, fails to

FIGURE 6-6 A data display representing individual specimen height with a vertical line.

difficult to read, especially from the back of the room. Will volunteered that the authors might consider alternating colors for different values, to make it easier to discern small changes in contiguous values.

The authors of the second display (Figure 6-7) simply ordered the values from lowest to highest and then wrote them along the bottom of the paper, stacking the values that occurred multiple times. The chart makers apparently ran out of room along the bottom of the page and, to avoid starting over, placed the remaining four values (200, 205, 212, 255) on the upper left, surrounded by a box. Although the values are separated by commas, this



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