Elimination 4 - multiply one equation only

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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.


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.

Play of the Day

40 minutes


10 minutes


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.