# Elimination 4 - multiply one equation only

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## Objective

SWBAT solve linear systems of equations using elimination, Day 4.

#### Big Idea

More practice! Get kids fluent in solving systems using elimination... and push them to begin thinking about which method works best in different situations.

## Warm-up

10 minutes

WU69 Elimination is similar to yesterday's challenging warm-up.

I sometimes like to include similar tasks two days in a row, to give kids "two bites of the apple." as their understanding develops.  I feel the second day really solidifies a learning, so that not every day feels like a foreign task.  In this case, students should apply the more efficient method of substitution of the coordinates to solve.

A new wrinkle is to ask early finishers to "prove" that if you solve the system you chose using elimination or substitution, it would yield the given coordinate point, which is a way to check your work (and also to demonstrate the beauty and symmetry of mathematics :)).

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

The homework file is a resource that generally includes 5-7 problems that consist of problems related to this lesson, as well as spiraled review.  I also give the kids the answers to the problems.

We sometimes give HW break packets to students over long breaks.  In this case, I chose sample problems that were multi-step, and good illustrations of the key standards we have learned thus far in the school year.

Sometimes, the HW file is a take-home assessment.