## Reflection: Modeling Writing Algebraic Expressions to Solve Perimeter Problems - Section 2: Guided Problem Solving

While working on the guided problem solving problems I noticed students sometimes having a difficult time making the equation.  To make it easier to see that we are adding three side lengths for a triangle I had them write _____ + _____ + _____ = _____.

This made it easier for them to see that they should have:

GP1) x + 2x + (x+12) = 52

GP2) x + x+2 + x+4 = 36

GP3) w + w + (w+5) + (w+5) = 40

Perhaps this could be something to put in the resource, though writing it in worked well.

On another note, I had one student who wrote gp2 as (x-2) + x + (x+2) = 36.  This brought up a lot of good discussion.  When solve we had a different value of x, but the same side lengths were found!  A few students decided to use this method in the independent section of work.

Modeling The Perimeter
Modeling: Modeling The Perimeter

# Writing Algebraic Expressions to Solve Perimeter Problems

Unit 4: Expressions and Equations
Lesson 19 of 20

## Big Idea: The sides of the triangle are x, (x+7), and 2x. The perimeter is 50 units. Find the lengths of the sides.

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Standards:
Subject(s):
Math, perimeter (Determining Measurements), writing equations, equations for perimeter
40 minutes

### Grant Harris

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