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        Part of Cyberchase
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        Balancing Number Sentences to Introduce Missing Values

        Students learn about balancing equations and keeping an equation balanced by adding/subtracting the same amount to both sides of the equation. Students solve missing value problems and justify their solutions.

        Lesson Summary


        Students learn that equations are balanced when the same number is on each side. This idea is explored in the CYBERCHASE video in the context of solving a security lock problem to overcome another of Hacker's plots. The students learn to conserve equality (keeping an equation balanced) by adding or subtracting the same amount to each side. This allows students to solve missing value problems with one or two terms and to justify their solutions.

        Grade Level:


        Suggested Time

        60 minutes

        Media Resources

        A Simple Balance QuickTime Video
        Balancing Equations with Multiple Terms QuickTime Video
        Solving an Equation for a Missing Value QuickTime Video


        Solving Equations for Missing Values Handout
        Assessment: Level A
        Assessment: Level B
        Answer Key

        The Lesson

        Part I: Learning Activity

        1. Read the following to your students: "Hacker is causing chaos by littering the cybersites with cyberstatic. The CyberSquad must solve three number puzzles in order to turn off the static. Each puzzle gets harder, so watch closely to be able to successfully solve the challenges on Handout 1after you watch the video clip."

        2. Tell the students that they will now watch three video clips in which the CyberSquad must solve number puzzles, each one more complicated than the last. After viewing a clip, discuss the method used by the CyberSquad to create a balanced equation. Replay the clip if necessary.

        3. Play the A Simple Balance QuickTime Video .

        4. Play the Balancing Equations with Multiple Terms QuickTime Video .

        5. Play the Solving an Equation for a Missing Value QuickTime Video .

        6. Distribute the Solving Equations for Missing Values Handout .

        7. Review the first example in the handout with the students. It is the same problem the CyberSquad encounters in video segment 3. Make sure the students understand how to justify the steps.

        8. Ask the students to complete the handout.

        9. When the students have completed the handout, review the handout with the entire class. Pay particular attention to Problem #2 in which the equation starts with a subtraction.

        Part II: Assessment

        Assessment: Level A (proficiency): Students solve simple balancing equation problems. 

        Assessment: Level B (above proficiency): Students solve more complicated balancing equation problems.


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