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Today’s Materials

  • calculator
  • pencil
  • notebook
  • glue

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Reasoning about Solving Equations

(part 1)

Lesson 7

Download for free at openupresources.org.

2019 Open Up Resources |

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Hanger Diagrams

Warm Up

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What do you notice? What do you wonder?

balanced

unbalanced

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In the two diagrams, all the triangles weigh the same and all the squares weigh the same.

For each diagram, come up with…

  • one thing that must be true
  • one thing that could be true
  • one thing that cannot possibly be true

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Let’s see how a balanced hanger is like an equation and how moving its weights is like solving an equation.

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Today’s Goals

  • I can find an unknown weight on a �hanger diagram and solve an equation that represents the diagram.
  • I can write an equation that describes the weights on a balanced hanger.
  • I can explain how a balanced hanger and an equation represent the same situation.

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Hanger and

Equation Matching

Activity 1

  • Think Pair Share

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On each balanced hanger, figures with the same letter have the same weight.

Begin with Quiet Work Time. (5-10 min.)

Share your thinking with a partner.

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7 = 3w + 1

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2z + 3 = 5

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3x + 2 = 3

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6 = 2y + 3

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Use Hangers

to Understand

Equation Solving

Activity 2

  • Think Pair Share

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Work on your own for �5-10 min.

Share your thinking as a team.

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7 = 3x + 1

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2y + 10 = 31

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6.8 = 2z + 2.2

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4w + 3/2 = 17/2

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“Are you ready for more?”

When you have the time, visit the site https://solveme.edc.org/Mobiles.html to solve some trickier puzzles that use hanger diagrams like the ones in this lesson. You can even build new ones. (If you want to do this during class, check with your teacher first!)

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Work with your team to draw a hanger diagram that corresponds with this equation:

4x + 6 = 9.2

After that, one partner should solve using the equation, and the other partner solves by reasoning with the diagram.

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How was solving the equation and diagram alike and different?

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Today’s Goals

  • I can find an unknown weight on a �hanger diagram and solve an equation that represents the diagram.
  • I can write an equation that describes the weights on a balanced hanger.
  • I can explain how a balanced hanger and an equation represent the same situation.

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Solve the Equation

Cool Down