8th Grade Math Lesson

The Pythagorean Theorem: From Right Triangles to Coordinate Distances

Shared by A STEM Educator

Grade 8 honorsBTC Style / Thinking Classrooms50 min

Learning Objective

Students will apply the Pythagorean Theorem to calculate missing side lengths of right triangles and determine exact distances between two points on a coordinate plane.

Lesson Overview

Students begin by identifying legs and hypotenuse in labeled right triangles, build to solving for missing sides using a² + b² = c², then transfer that skill to finding exact distances between points on a coordinate plane — connecting geometry to algebra.

Materials

Vertical whiteboards or large chart paper
Dry-erase markers (multiple colors)
Pencils and scratch paper
Basic calculator (phone calculator is fine)

Scaffolded Task Progression

1Task 1

The right triangle below has legs labeled

a

and

b

, and hypotenuse labeled

c

. The legs measure

a = 3

and

b = 4

. Use

a^{2} + b^{2} = c^{2}

to find

c

.

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

2Task 2

The ramp from the launch: the rise is

5

ft and the run is

12

ft. Find the exact length of the ramp board (

c

).

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

Unlock the full lesson

See all 7 scaffolded tasks, the full answer key, warm-up, exit slip, and a print-ready version — free to start.

Create a free account

Already have an account? Sign in

Make it your own

Like this lesson but want to tweak it?

Make an editable copy and adjust the tasks, warm-up, and answer key to fit your class — no need to start from scratch.

Generate a new lesson