Data and Graphs

• From the beginning of the unit, discuss with students the pertinence of the material. Ask them to look for and share examples of data and graphs that they see in everyday life. Perhaps students can find poll results reported in television or the on the Internet. They might peruse almanacs to find interesting data sets. For extra credit, they might research the use of statistics in sports or other real-life areas, write up and illustrate what they found, and share their information with their classmates.

• Ask a high school athlete or coach to talk to your class about statistics that are kept in particular sports and how the results of the data are used to help improve performance. In a similar vein, you night ask your food-service director to talk to your students about data that tracks and guides choices of foods that are offered.

• Whenever possible, let students collect, organize, and display their own real data. You might have individuals or partners plan how to poll classmates for "favorites"—anything from favorite desserts to recordings to sports to toothpastes. Allow class time for students to ask classmates for information and make charts and graphs of it. Then a day or two later, let students show and explain their results.

• You might be able to place a poll box outside your classroom or visit another classroom to gather data. Help your students plan ways to make specific questions or choices for participants. Once data are gathered, have students organize, display their results, and share the results via a bulletin board display. Encourage them to have a "show-and-tell" session with the other class.

• When helping students interpret data charts and graphs, use an open-ended question such as, "What does the graph show?" to open the discussion. Let several students offer answers, then pursue specific questions, such as "Which category had the most?" "What was the difference in ____(category) and ___?" "What was the range of the data?" and "Why is this chart or graph suitable for the data?"

• As your students make charts and graphs of data, have them title the graphs and label the axes.

• To generate numbers for stem-and-leaf plots, let students work with partners to toss two number cubes. One cube can represent the tens digit and the other can represent the ones digit. Extend the discussion of the results to include questions such as these: What does the stem-and-leaf plot show? Why might the results have happened the way they did? (Using cubes with 1-6 on the faces, students will tend to get about the same number of numbers in the tens, twenties, thirties, forties, fifties, and sixties because the chances of getting a 1-6 in the tens place is the same.) What were your chances of getting numbers in the seventies or eighties? (These are impossible with 1-6 cubes. Also impossible are numbers with 7, 8, 9, and 0 in the ones place.)

• To gather data for histograms, let students find data such as this: Prices of different brands and weights of bread; the number of calories per serving found on food labels; number of attendees at various school or sporting events; or any other data that students suggest.

• To make line graphs or double line graphs, students might gather data on topics such as these: indoor and outdoor temperatures, morning and afternoon temperatures, attendance for one- or two-week periods, and numbers of students bringing lunch or buying lunch over a two-week period.

• As you teach each type of graph, talk about its advantages and data for which it is appropriate. Then students will have a background of information when you reach the point of choosing different graphs for different data sets.

• Give students opportunities to show the same data two or more ways—on a chart and a graph, or on two or more different types of graphs. As students show their results within small groups or to the class, prompt them to explain the appropriateness of the charts or graphs that they have chosen.