Use a display of the Help Improve This Graph Master that shows a graph with several errors and omissions to review features of good graphs. Students can compare the flawed graph with a correct bar graph of the same data, Room 204's Main Interests, shown in the Student Guide. Students should identify the following flaws:
- Axes are not labeled with the names of the two variables.
- The graph does not have a title.
- Lines, not spaces, should be labeled with numbers.
- Scaling by 5s is not a good choice. Since eight is the largest value, scaling by ones is possible and makes the graph easier to read. There is no need to scale up to 100 students because there are only 22 students in the entire class.
Have students compare the graph in their Student Guide to the graph on display.
- Which graph makes it easier to know how many students preferred each activity? Why? (The graph in the Student Guide is easier because each number has a line. On the display, it's harder to tell exactly how much it is when the bar doesn't land on a number. For example, do 3 or 4 students like animals?)
- Which graph do you think tells the story better? Why? (The graph in the Student Guide makes it very easy to see the story of the data because the differences between the bars stand out more.)
Ask students to compare the different representations of the data that were used in the lesson.
Ask some of the following questions:
- Why did we make the second table? (The big table was just a long list. It was hard to understand the infomation.)
- What could you see in the second table that you would not easily see in the first table? (The values that occurred most often and least often. In Room 204's data, the values with the most tallies told us the most common main interest.)
- What could you see in the first table that you would not see in the second table? (The answers of each person. The second table only tells us how many people answered in each category. It didn't tell what each person answered.)
- What do you see in the bar graph that you could not see as easily in the tables? (The bar graph is like a picture. It makes it easier to compare sizes of the numbers.)
