Jeff Li MTP KIPP Infinity Charter School, NEW YORK, NY
8th Grade Math : Unit #5 - SYSTEMS OF LINEAR EQUATIONS : Lesson #1

Solve systems of linear functions by graphing - TWO lines on the same graph?!?

Objective: SWBAT solve systems of linear equations by graphing.
Standards: 8.EE.C.8 8.EE.C.8a 8.EE.C.8b MP2 MP6 MP7
Subject(s): Math
60 minutes
1 Warm-up - 10 minutes

Each day, students complete a warm-up that spirals older material in with content from the previous lesson. Warm-up problems sometimes extend content that students have encountered before to more unfamiliar contexts.

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

Today, to save time for a longer Play of the Day, we are reviewing HW as our warm-up.


2 Play of the Day - 40 minutes
Making note of structure with systems of linear equations
High Quality Task

I like using the SILVER question (see the resource section of this reflection for the question and a sample of student work) to push the use of structure (MP7) right away in the beginning of this unit.  I ask students to create (not choose) a line that will have one solution, no solutions, and infinite solutions with a given line, which reinforces the idea that in any system, there are three possibilities for intersection, and that the only thing that matters when trying to determine which is the case is the rate of change of each line.  I think this implants and embeds an important conceptual understanding right at the outset of this unit, which lives on throughout the unit, before we get into the deep algebra of substitution and elimination.

4 Homework - 15 minutes

HW60 Solve systems of linear functions by graphing includes problems related to this lesson, as well as spiraled review.  I also give the kids the answers to the problems.

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