Seventh Grade · Math · week 7

Scale drawings

Use a scale to compute actual lengths from a scale drawing, and drawing lengths from actual measurements.

A scale drawing shrinks or enlarges something real by the same factor everywhere, and the scale tells you exactly how. A scale like "1 in = 8 ft" means every inch on the drawing stands for 8 real feet.

To go from drawing to actual, multiply by the scale factor. To go from actual back to drawing, divide by it instead. Always double check which direction a question is asking for before you multiply or divide.

📋 For the teacher
Teach it (10–15 min):
  • Write the scale as a little table (1 unit on paper = however many units in real life) and refer back to it for every problem.
  • Practice both directions on purpose -- drawing-to-actual and actual-to-drawing -- since real problems mix them.
  • Watch unit conversions closely, like turning 150 cm into 1.5 m, since scale problems often end in a different unit than they start.
  • Measure something real (a room, a book) and sketch it at a scale you choose together.
Talk about it:
  • How do you know whether to multiply or divide by the scale factor?
  • Why might a map use a scale like 1 cm = 25 km instead of drawing things full size?
  • What can go wrong if you forget to convert units at the end of a scale problem?

Mastery looks like: They correctly convert between drawing and actual measurements in both directions, including any needed unit conversion.

Common stumbles: Multiplying when they should divide (or the reverse); forgetting a final unit conversion.

Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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