ADDITION EQUATIONS - BALANCE SHEET

Procedure:

Many of the equations can be solved mentally, therefore emphasize that the lesson will focus on a process for solving equations. Explain that understanding this process for solving equations will help them solve more difficult equations that cannot be worked mentally.

Divide the class into groups, provide each group with approximately 30 two color chips. Provide each group with a sheet of unlined 8 x 11 paper and have them draw a line dividing the paper in half, creating their balance sheets. Write the equation x + 3 = 10 on the overhead below the balance sheet and show its model. Place one yellow and 3 red chips on the left side of the line and 11 red chips on the right side of the line.

Tell the students to think of the two sides of the line as the two sides of a balance scale. Explain that it is very important to keep both sides of the balance sheet or scale balanced. Emphasize that as long as the same work is performed on both sides of the line a balance is maintained.

Stress the importance of showing each step. Explain that the yellow chip is the variable x or unknown number. Work the problem on the overhead showing each step by modeling it with chips.

		
  x + 3 = 11     (Write the equation.)
x + 3-3 = 11-3  (Write & model the need to subtract 3 from both sides.)		   
      x = 8     (Write the new equation.)
Have the students model several other simple addition equations using chips. Ask the students to record their steps for each equation as they model it with chips.

CRPC

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: parasch@cs.rice.edu

These pages were developed through GirlTECH, a teacher training sponsored by the Center for Research on Parallel Computation (CRPC), a National Science Foundation Science and Technology Center.
Thanks to the RGK Foundation and EOT-PACI for its generous support of GirlTECH.