Last catch-up post from December; our cheese pies & drinks problem for linear systems in the Grade 10 applied class. Overview:I’ll break it down into the 3 acts.

**Act 1: Notice, wonder, & estimate**

*What do you notice & wonder?*

**Act 2: Data collection & solving**

Presented the class with the cost of each order:

Groups went to their boards to solve:All of the groups subtracted the smaller order from the larger order twice in order to eliminate the cheese pies and leave the cost of 2 drinks, from which they easily determined the cost of 1 drink. Then went back to calculate the cost of a cheese pie.

**Act 3: Answer check / resolution / consolidation**

We confirmed that every group had the correct answer:

Then I did some direct teaching on how to use the elimination method when you need to multiply one of the equations in order to eliminate a variable:

We discussed how the multiplying of “her” equation by 2 mimics how my students subtracted the smaller order two times in their solutions.

**Day 2**

We consolidated our learning about the elimination method by describing each step in the solution. Handout here.

They had time to complete the homework on Khan Academy here.

As always, the full folder of materials for this activity is here.

– Laura Wheeler (Teacher @ Ridgemont High School, OCDSB; Ottawa, ON)

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