### Lesson Plan

# Graphical Representation of Data

Students will learn to construct and interpret line plots, stem-and-leaf plots, and box-and-whisker plots, and use these to find measures of central tendency and answer critical-thinking questions.

Grades

6–8

Duration

60 MINUTES

### Objectives

**Students will:**

- Use statistical information to construct line plots
- Use statistical information to construct stem-and-leaf plots
- Use statistical information to construct box-and-whisker plots

### Materials

- Cultivating Data Worksheets: Line Plots, Stem-and-Leaf Plots, and Box-and-Whisker Plots printable

- Answer Key: Cultivating Data Worksheets printable

- Standards Chart: Cultivating Data printable
**Optional:**Interactive Data Analysis Tools**Optional:**Cultivating Data: Organize, Display, and Analyze Statistical Information Classroom Poster printable

**Note:** The lesson is based on the assumption that students have a working knowledge of mean, median, mode, and range. If needed, the Measures of Central Tendency lesson plan covers these topics.

### Set Up

- Make a class set of the Cultivating Data Worksheets: Line Plots, Stem-and-Leaf Plots, and Box-and-Whisker Plots printable. The printable contains three separate worksheets, one about each type of plot.
- Print a copy of the Answer Key: Cultivating Data Worksheets printable.
**Optional:**Make a copy of the Cultivating Data: Organize, Display, and Analyze Statistical Information Classroom Poster printable to display in your classroom, or print a class set for students as a reminder for vocabulary and different types of graphs.

### Lesson Directions

**Step 1:** Ask the class how many phones they have in their homes. Have students respond one at a time and record each answer on the board. (Note that any similar question that works for your particular class will serve the purpose.) Ask if there is a way to organize the data on the board.

**Step 2:** If it isn't mentioned, suggest a *line plot*. Demonstrate how to construct a line plot. First, find the smallest and largest answers, and then construct a number line with the smallest value at one end and the largest at the other. Draw an "X" on the number line for each answer, with duplicate responses placed above previously recorded responses.

**Step 3:** Point out how to use the plot to find the *range*, *mode*, and *median*. Review the meaning of these terms as necessary.

**Step 4:** Indicate that a line plot can be useful when range of the data isn't very wide. To provide an example of data with a wider range, write the points scored by the San Antonio Spurs in games they played in April 2013* on the board: 90, 98, 88, 99, 86, 108, 86, 106, 95, 91, 102, 120, 103. (*Feel free to select statistics for a team you and your class support!)

**Step 5:** Demonstrate how to construct a *stem-and-leaf* plot from the data on the board:

**Step 6:** Point out how to find the range, mode, and median using the plot and remind the class how to find the mean.

**Step 7:** Indicate to the class that a *box-and-whisker* plot is another way to display and analyze data. Write fictitious test scores for two classes on the board:

**Class 1:** 30, 75, 75, 80, 80, 85, 85, 85, 90, 95, 95

**Class 2:** 50, 60, 65, 70, 75, 75, 80, 85, 85, 90, 100

**Step 8:** Ask how the performance of the two classes can be compared.

**Step 9:** Demonstrate how to construct a box-and-whisker plot for each class, showing how the five points of *minimum*, *first quartile*, *median*, *third quartile*, and *maximum* are determined and displayed as follows:

**Step 10:** Discuss how Class 1, even though their highest and lowest scores were below Class 2, can be considered to have performed better because the middle two quartiles are higher on the number line.

**Step 11:** Distribute the Cultivating Data Worksheets: Line Plots, Stem-and-Leaf Plots, and Box-and-Whisker Plots printable to students to complete over 1–3 days. Use your copy of the Answer Key: Cultivating Data Worksheets printable to review answers with class.

### Standards

**Grade 7:**CCSS.Math.Content.7.SP.B.4**Grades 6-8:**NCTM Data Analysis and Probability

For more information, download the comprehensive Standards Chart: Cultivating Data printable.