8th Grade Math Lesson

Slope and Y-Intercept: From Graphs to Equations

Shared by A STEM Educator

Grade 8 honorsBTC Style / Thinking Classrooms50 min

Learning Objective

Students will determine slope and y-intercept from graphs, tables, and two points, then write and interpret linear equations in slope-intercept form ( $y = m x + b$ ).

Lesson Overview

Students progress from reading slope and y-intercept directly off a graph, through calculating slope from two points, to writing and interpreting equations in slope-intercept form — including negative, fractional, and contextual slopes.

Materials

Vertical whiteboards or chart paper
Dry-erase markers (multiple colors)
Rulers
Printed coordinate grids (backup for students who prefer graphing on paper)
Random grouping cards

Scaffolded Task Progression

1Task 1

The line below passes through the two marked points. Count the rise and the run between them. What is the slope?

[ Interactive graph / diagram, available in the full lesson ]

2Task 2

Find the slope of the line through these two points. Then find where the line crosses the y-axis (the y-intercept).

[ Interactive graph / diagram, available in the full lesson ]

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