Grade 7 · Unit 2Topic 2 of 3~22 min

Proportional Relationships & k

Spot proportional relationships and find the constant of proportionality.

Step 1 · Learn

Walkthrough

Read this first — it covers the idea in plain language with a worked example.

Two quantities are proportional when their ratio is always the same. On a graph, that means a straight line through the origin (0, 0).

Worked example

A table shows (2, 8), (3, 12), (5, 20). Find k and write the equation.

Tip

The constant of proportionality is the same as the unit rate — the value of y when x = 1.

Step 2 · Watch

Watch the main video, then check the second take if you want another explanation.

Khan Academy

Write y = kx and find the constant of proportionality.

Khan Academy

How to tell when two quantities grow together at a steady rate.

Step 3 · Practice

Try a worksheet or work through some problems before the quiz.

Step 4 · Check

A couple of questions to make sure this topic stuck. Retake as many times as you want.

Proportional Relationships & k

Easy

A proportional relationship contains the point (4, 28). What is the constant of proportionality?