## Reflection: Developing a Conceptual Understanding SUB! How can we use the properties of algebra to figure out the intersection of two lines WITHOUT graphing? (Day 1 of 3) - Section 2: Play of the Day

This year, as I taught substitution, I used a strategy that accelerated the rate at which my students were able to solve systems using this method.

I used the SMART Board to create the equations, say y = 2x + 1 and 3x + 4y = 10.  I then circled the Y (the isolated variable) and asked kids, " What is this equivalent to?"  "2x + 1."

Then, I said that we could substitute the 2x + 1 into the other equation, "where?"  "Where the y is."

Then, I would use black to rewrite the second equation, but use red for the y.  This would make the y a separate object from the rest of the equation.  Then, I could "substitute" the y out and bring in (2x + 1) in red, and put it in the correct place in the equation.  I could move the y and the (2x + 1) back and forth to show that they were interchangeable.  This helped my students, especially my lower students, increase their proficiency ENORMOUSLY as I taught these lessons.

Using a Dynamic SmartBoard to Demonstrate Substitution
Developing a Conceptual Understanding: Using a Dynamic SmartBoard to Demonstrate Substitution

# SUB! How can we use the properties of algebra to figure out the intersection of two lines WITHOUT graphing? (Day 1 of 3)

Unit 5: SYSTEMS OF LINEAR EQUATIONS
Lesson 3 of 19

## Big Idea: SUB! How can we use the properties of algebra to figure out the intersection of two lines WITHOUT graphing?

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Subject(s):
Math, substitution method, Algebra, Systems of Equations and Inequalities, equality, Solving Systems of Equations
75 minutes

### Jeff Li MTP

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