## Reflection: Intervention and Extension Solving Addition and Subtraction Equations Using Models - Section 2: Guided Problem Solving

Many of my students first learned to solve equations by solving pan balance problems.  I found an applet that has a virtual pan balance allowing for negative numbers.  The interface is a bit clunky and you must use numbers of a low magnitude (less than 10?), but it is useful tool that you may want to use in order to provide a visual image for students.

To create the equation x + 2 = -3, I clicked the button "Create Problem".  A window pops prompting you to enter values.  The bold values are what I had to enter, the non bold are what is given.

1x + 2 = 0x + -3

I entered 1, 2, 0, and -3.  See what I mean by clunky?  Next, you are prompted to drag quantities to make the equation.  I like how negative values are shown as balloons that can lift one side of the scale.  See this image.

Unfortunately, it does not allow you to drag on tiles to solve.  You have to click "continue" to solve.  Here you would add -2 to both sides, so enter -2 into the prompt.  Before doing this, I would suggest having students model this with their algebra tiles while the pan balance equation is displayed on the SmartBoard.  Students then see they need to add -2 to solve.

All of this could be done on paper as well but the nice thing about the applet is you can see how the scale tips based on various values.

Intervention and Extension: Pan Balance

# Solving Addition and Subtraction Equations Using Models

Unit 4: Expressions and Equations
Lesson 5 of 20

## Big Idea: Through modeling with tiles and drawing students come to see how inverse operations can be used to solve equations.

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5 teachers like this lesson
Standards:
Subject(s):
Math, Expressions (Algebra), One, inverse operations, algebra tiles, equation
50 minutes

### Grant Harris

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