# Elimination 3 - multiply one equation only

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## Objective

SWBAT solve linear systems of equations using elimination, Day 3.

#### Big Idea

Get kids to stand up or sit down as they become fluent in multiplying one equation before using elimination.

## Warm-up

10 minutes

The Lesson 5 - 9 Warmup challenges students to use reasoning, rather than process to understanding the solution to a system of equations. The task asks the students to identify the correct partner equation to form a system with a given solution.

I like this task because it pushes kids to figure out a more efficient way to solve the problem, one that requires a deeper understanding of what a solution to a system of linear equations actually is.  It is NOT efficient to solve each system (four times) to determine if the point (4, -5) is a solution.  Rather, if kids understand that solutions make each of the equations true, all a student has to do is substitute in the coordinates into each equation to determine which one is the correct equation.

I further throw the kids by giving them a ton of space.  This "tricks" them into thinking that this question requires a ton of work... I emphasize that they should not be robots, and should always think before they tackle a problem with a set of procedures.

For a video narrative about how I structure each lesson, and how the warm-up fits in, click here.

40 minutes

10 minutes

## Homework

15 minutes

HW68 Elimination 3 - multiply one equation only includes 5 problems. Four are related to this lesson, one is spiraled review.  I also give the kids the answers to the problems.