Box Plots

Abstract

The goal of this lesson is to introduce box plots and quartiles. An activity and discussion with supplemental exercises help students learn how data can be graphically represented.

Objectives

Upon completion of this lesson, students will:

  • have reviewed the concept of median
  • have learned how to calculate quartiles for any size data set
  • have learned how to build a box plot

Activities

This lesson introduces students to box plots through the following activities:

Standards

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

  • Probability and Statistics
  • Mathematics as Reasoning
  • Computation and Estimation

Key Terms

This lesson introduces students to the following term through the included discussions:

Student Prerequisites

  • Arithmetic: Students must be able to:
    • put numbers in order from smallest to largest
    • calculate the average of two numbers
  • 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 for the box plot activity's built in data sets
    • Worksheet for working with the data collected from the class (see below).

    Lesson Outline

    1. Remind students of the ideas behind means and medians, as covered in the Mean, Median and Mode discussion.
    2. Walk students through the construction of quartiles, the five-number summary and box plot construction as in the Box Plot discussion.
    3. Have students experiment with the built-in data sets available in the Box Plot activity to be sure that they understand how to read the the box plots. Questions for the data sets can be found in the worksheet.
    4. Have the students collect the following data from each other:
      • Gender
      • Height
      • Length of ride/walk to school in minutes
      • Estimate number of hours of TV watched in a week
    5. Have the students explore the questions on box plots by building the appropriate box plots either by hand or using the Box Plot activity. With less mature students, it would be best to help them decide which box plot to graph for each question.

    Alternate Outlines

    This lesson can be rearranged in several ways.

    • Students can be asked to work with the notion of outliers, as can be done with the Box Plot activity.

    Extensions

    If the students have not yet seen histograms, the lesson on Histograms and Bar Graphs makes a good follow-up. For more advanced students, The Bell Curve, covers the normal distribution and the bell curve controversy.

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