Scale drawings and scale factor
- Which copies a zoom could make — 3 tasks
- Add three, or multiply by 1.75 — 3 tasks
- The factor, and what it does to angles — 3 tasks
- Which way round — 3 tasks
- Going Deeper — 6 tasks
- Practice — 24 tasks
- Summary — 2 tasks
- Cool-down — 3 tasks
Classroom activities
Things a class does rather than writes on. Each one is a finished PDF: print it, cut it up if it says so, and hand it round.
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Is It Really a Scale Drawing? — Cut & Glue Sort 25 minutes, including the cutting · 5 sheets
12 pieces, each giving facts about an original and a drawing of it, sorted into "it is a scale drawing", "it is not a scale drawing" and "cannot tell: the facts are not enough". The second row holds the lesson's mistakes as facts (adding 3 cm to every side, a stretch one way, an angle that changed), and the last row holds what students accept too soon: one pair of sides, four sides with no angle, matching angles alone, and two perimeters.
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Multiply, or Just Add? Scale Drawings and Scale Factor — Answer Maze 10–15 minutes · 4 sheets
8 boxes on one page. Half find a scale factor, from a pair of lengths or from a scale such as 1 inch to 4 feet; half use a factor on a side or an angle. The wrong answers are the lesson's big mistakes: dividing the wrong way round, leaving out the units, adding the difference instead of multiplying, and multiplying an angle. The row of box numbers at the foot is the check.
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Bigger or Smaller, and From Which One? Scale Factor — Mystery Picture 20–30 minutes · 4 sheets
25 squares, each an original and a scale drawing of it drawn to one scale, with a sentence such as "From the drawing to the original, the scale factor is 40%". Fill the square only if the sentence is true. The original is the bigger figure in about half the squares, the sentence runs the other way in about half, and the factors are whole numbers, fractions, decimals and percents. When every square is right, a picture appears.
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How Many Times Bigger, and Which Way? Scale Drawings and Scale Factor — Scavenger Hunt a full class period · 13 sheets
16 cards around the room, each with a triangle marked ORIGINAL and a scale drawing of it marked DRAWING. Some cards ask for the scale factor from one figure to the other, in either direction; the others ask for a missing side. Dividing the wrong way round, or adding the difference instead of multiplying, lands on a card that sends the group back, and a clean run is 8 lines on the record sheet.