Volume of Prisms

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This lesson is designed to introduce students to the concept of volume and how to find the volume of triangular and other shape prisms.

This lesson is designed to follow the Volume of a Rectangular Prism lesson.


Upon completion of this lesson, students will:

  • have reinforced the concept of volume.
  • understand how to solve problems for the volume of triangular prisms.
  • understand a generalization for solving for the volume of all prisms.

Standards Addressed:

Textbooks Aligned:

Student Prerequisites

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

Teacher Preparation

  • Physical manipulative objects as examples of triangular prisms
  • Access to browser for pairs of students
  • Paper and pencil
  • Student copies of Record Sheets

Key Terms

volumeA measure of the number of cubic units needed to fill the space inside an object

Lesson Outline

  1. Focus and Review

    Remind students what has been covered in previous lessons and have students review the following:

    • Area of shapes (rectangles, triangles, circles, etc)
    • Basic concept of volume
    • Volume of rectangular prisms

  2. Objectives

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

    • Today we are going to be extending our discussion from yesterday about volume. Instead of looking at the volume of rectangular prisms, we are going to be generalizing the process for all prisms.
    • We will continue to use the Surface Area and Volume applet, but please don't open your computers until I instruct you to do so.

  3. Teacher Input

    • Lead students in a discussion about a generalized approach to finding the volume of all prisms.
    • Be prepared to show students physical models of different prisms and identify the base shape.

  4. Guided Practice

    • Introduce Surface Area and Volume applet to any students who are unfamiliar with the applet.
    • Make sure that students are using Triangular Prism from the drop-down menu.
    • Before students begin working on the applet, be sure to point out the Slant Height component on the applet and explain that this measurement is not necessary for today's activity.
    • Note: If students will be using the Compute mode for finding only the volume of the prisms and not the Surface Area and Slant Height, show the students the pop-up box that will appear indicating that the Surface Area input is incorrect.

  5. Independent Practice

  6. Closure

    • You may wish to bring the class back together to discuss any problems that were especially hard for students to solve. Once the students have been allowed to share what they found, summarize once more the main points of the lesson.
    • You can also ask students to brainstorm definitions for surface area as a lead in to future lessons.

Alternate Outline

This lesson can be rearranged if there is only one available computer.

  • Instead of having students complete Record Sheet in pairs, display the Compute mode on a classroom computer, record the dimensions on the whiteboard, and have students work independently to solve for the volume. When students have computed the volume, have one student enter the number to check answer.

Suggested Follow-Up

  • This lesson can be followed by a series of lessons on the Surface Area of prisms: Surface Area of Rectangular Prisms and Surface Area of Prisms
  • Alternately, this lesson could be followed-up by lessons on volume of other three-dimensional figures such as pyramids, cones, cylinders, and spheres.

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