8 t h Grade
Proportional Relationships
Module 3
The Destination
Standards
Module 3 revisits proportional relationships and
introduces the concept of slope. In seventh
grade, students identified the constant of
8.EE.B.5
8.EE.B.6
8.F.A.2
8.F.B.4
Graph and interpret unit rate as the slope
and compare two proportional relationships
represented in different ways.
proportionality (k) as the unit rate for graphs of
lines through the origin (y=kx). In eighth grade
unit rate is referred to as (m), or slope, since both
proportional and eventually, nonproportional
Write the equation for graphs of
proportional relationships (y=mx+b, b=0).
Use similar triangles to show slope between
two points.
relationships are studied. Students name the rise
Compare functions represented in
different ways (equation, table, graph, or
verbal description).
words, its steepness. By tracking the rise and
Determine the rate of change (slope) from a
table or a graph.
and run between two points on a line, and write
this as a ratio. This ratio shows how the line
changes vertically and horizontally, or in other
run using another set of points along the same
line, students create similar triangles to prove
that the ratio is constant. From graphs,
equations, and tables, students name the
constant rate of change (slope).
Must-See-Attractions
Slope Triangles
Models
Connect students’
understanding of similar figures

Tables

Graphs
activity. Students cut out grid-

Equations (y = mx)
paper right triangles and find a

Slope Formula
𝑦2− 𝑦1
𝑥2 − 𝑥1
pair that can be placed along a
to slope with this kinesthetic
straight line. Compare the
ratios of height: base. For
which triangles are these ratios
equivalent?
Related Places to Visit
Scale Drawings
For an art project, Jacob enlarges a drawing of SpongeBob SquarePants by 300%.
The original dimensions of SpongeBob are 4 inches by 3 inches. What are the new
dimensions?
Proportional Graphs in Quadrants II, III, or IV
Stanley was digging holes at Camp Green Lake. He earns $5 for every 2 feet that he digs. Represent
this information as a table, graph, and an equation. Is this similar to the graphs you have seen in
class? Why or why not?
SMP
Algebra
1. Solve for x:
𝑥−6
=4
5−3
Proportions
Which are proportions? How do you
2. The slope of a line is 2. The line goes
know?
1.
2.
through (6, 5) and (3, b). Solve for b.
3 12
=
4 16
7
4
=
10
12
Solve for the unknown.
1.
2.
𝑥 72
=
4 36
𝑥−2
2
=
EXIT
PARCC
15
6