Stem-and-Leaf Plots

Abstract

This lesson is designed to introduce students to stem-and-leaf plots.

Objectives

Upon completion of this lesson, students will:

• have been introduced to the notion of stem-and-leaf plots.
• have learned the terminology used with stem-and-leaf plots.
• have used stem-and-leaf plots to calculate the mean, median, and mode of a set of data.

Activities

• Stem-and-Leaf Plotter

Standards

The activities and discussions in this lesson address the following Standards:

• construct, read, and interpret tables, charts, and graphs
• systematically collect, organize, and describe data
• collect, organize, and present numerical data in a variety of forms (stem and leaf plots, box and whiskers, scatterplots, etc.)

Key Terms

Student Prerequisites

• Arithmetic: Students must be able to:
  • perform integer and rational arithmetic
• Technological: Students must be able to:
  • perform basic mouse manipulations such as point, click and drag
  • use a browser, such as Netscape, for experimenting with the activities

Teacher Preparation

Students will need:

• access to a browser
• pencil and paper
• copies of supplemental materials for the activities:
  • Worksheet To Accompany "Stem-and-Leaf Plots"

Lesson Outline

1. Focus and Review

   Remind students what has been learned in previous lessons that will be pertinent to this lesson and/or have them begin to think about the words and ideas of this lesson:

   Entertain a discussion about mean, median, and mode with the class. If this has already been covered, ask the class to recall what was learned about the topics.

2. Objectives

   Let the students know what it is they will be doing and learning today. Say something like this:

   • Today, class, we will be talking about stem-and-leaf plots which are used to help us statistically analyze sets of data.
   • We are going to use the computers to learn about stem-and-leaf plots, but please do not turn your computers on or go to this page until I ask you to. I want to show you a little about the program first.

3. Teacher Input
   • When the students understand mean, median, and mode, lead the class in a discussion of stem-and-leaf plots.

   • Open your browser to Stem-and-Leaf Plotter in order to demonstrate this activity to the students.

   • You may choose to model entering a set of data into the Stem-and-Leaf Plotter. Ask the class to suggest scores that might have been made on the last math test in the class.

   • After entering the data into the activity, you may choose to have a student explain to the class what the stem-and-leaf plot means. Have the student use the correct terminology when explaining the plot.

   • Ask the class for questions and be sure that everyone understands how to use the applet.

4. Guided Practice
   • Once you have verified that there are no questions regarding the use of the applet, pass out the Worksheet to accompany "Stem-and-Leaf Plots"

   • Walk the students through entering the data and finding the mean, median and mode for problem number 1.

5. Independent Practice
   • Have the students finish the worksheet. Allow the students to work independently or in small groups as you monitor the room for progress.

6. Closure

   You may wish to bring the class back together for a discussion of the findings. Once the students have been allowed to share what they found, summarize the results of the lesson. It is important that every student know the correct answers to the worksheet in order to fully understand stem-and-leaf plots. In particular, ask them to think about what it means for the mean to be bigger than or smaller than the median. Have them look at their plots and see that if the data are symmetric, the mean and median are close together, if there are extreme low values the mean is pulled down, and if there are extreme high values the mean is pulled up.

Alternate Outlines

This lesson can be rearranged in several ways.

• The students may create their own sets of data to enter into the Stem-and-Leaf Plotter.

• Students may challenge a friend to find the mean, median, and/or mode of a set of data that they find or create.

• You may rearrange this lesson to meet the needs and ability levels of students in your classroom.