Jeff Li MTP KIPP Infinity Charter School, NEW YORK, NY
8th Grade Math : Unit #4 - INTERPRETING AND COMPARING LINEAR FUNCTIONS : Lesson #1

# Define and graph linear functions

Objective: SWBAT define and graph linear functions
Standards: 8.EE.B.5 8.F.A.3 MP2 MP6 MP7 MP8
Subject(s): Math
60 minutes
1 Warm-up - 10 minutes

Each day, students complete a Warm-up that usually consists of spiraling the previous day's material, in addition to older material.  Warm-up problems also sometimes extend lessons 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 Warm Up.

In this case, the warm-up addresses a problem that many students missed on the last unit assessment.  Only one of them has a negative slope... and so the question I ask to open is:

"In which of these cases should there be a positive slope?"  We then analyze the incorrect answer choices to finally arrive at the correct answer choice, a strategy I often use.

Because students often have only an emerging understanding that positive slopes represent a positive association (in other words, as x increases, y increases also) - this is a wonderful learning opportunity to continue to develop this understanding.

2 Play of the Day - 40 minutes
What is a line? Working toward multiple representations

This year, I decided to focus on the idea of multiple representations of the same line - a line is NOT just a line on a graph, but a relationship between two quantities that has a constant rate of change.  I had students create their own line in slope-intercept form, and then graph the line, create a table from that line, and create a verbal description of the line, pushing on their creativity.  I really think it pushed on their understanding of what a line is, a key idea underlying the major work of 8th grade.

And all you need is some graph paper! :)  See the resource section for some examples of student work.

3 Huddle - 10 minutes
Using Thought Bubbles To Demonstrate Understanding
High Expectations
4 Homework - 15 minutes

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

Tonight's homework assignment: 4 - 1 HW40 Define and graph linear functions