Grade 7 · Unit 4Topic 1 of 4~20 min

Scale Drawings

Use a scale factor to relate a drawing to the real object.

Step 1 · Learn

Walkthrough

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

What a scale factor does

A scale factor tells you how many times bigger or smaller a drawing is than the real thing. A factor of 2 doubles every length; a factor of 0.1 shrinks everything to a tenth.

Worked example

A map uses a scale of 1 cm : 50 km. Two cities are 4 cm apart on the map. How far apart are they really?

Each cm represents 50 km.
4 cm × 50 km/cm = 200 km.

Tip

Corresponding lengths scale by the scale factor, but areas scale by the factor squared.

Step 2 · Watch

Video walkthrough

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

Khan Academy

Corresponding Parts of Scaled Copies

Identify matching sides and find the scale factor.

Watch on YouTube

Khan Academy

Interpreting a Scale Drawing

Use a scale to convert drawing lengths to real lengths.

Watch on YouTube

Step 3 · Practice

Practice

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

Khan Academy

Scale drawings

Open resource

Step 4 · Check

Quick check

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

Scale Drawings

Question 1 of 2

Easy

A scale is 1 in : 8 ft. A wall is 3 in long on the drawing. How long is it in real life?

Back toUnit 4 overview Next up · Topic 2 of 4Angle Relationships