1. 5.4: Scale Drawings

2. Scale Factor
The relationship between measurements on the drawings can be described by using a scale factor.
When you make a drawing twice as wide and twice as tall, your scale drawing has a scale factor of 2:1.
1/2 inch on the original =
1 inch on the scale drawing.

3. measurement on model : measurement on actual or original
Scale Factor
So, the scale factor is always written as
measurement on model : measurement on actual or original Or
Original: Each square = ½ inch Drawing: Each square = 1 inch
Scale Factor: 2:1 or 2/1

4. Simplifying the Scale Factor
Original: Drawing:
Each square= 1/2 inch Each square = 1/4 inch
What is the scale factor on the smaller scale drawing of Calvin?

5. Scale Factor Scale factors are usually expressed using 1 unit.
Real Eiffel Tower:
324 meters tall
LEGO Eiffel Tower: meters tall.
Instead of writing
1.08 : 324,
we write
1 : 300
or 1/300

6. Common Scale Factors
House Plans/Floor Plans: ¼” scale, which means 1/4 inch stands for 1 foot: 1:48.
N scale model trains: 1:148.
Hot Wheels: 1:64
Radio-controlled car: 1:10
Traditional Dollhouses: 1:12, 1:18, or 1:24
Barbie Dollhouse: 1:6

7. Using scale factors: Practice

8. Scale Models and Drawings are Proportional
The reason a scale model or scale drawing looks similar to the actual or original thing is that all measurements on the model/drawing are proportional to measurements on the actual/original.
This means that every part of the drawing is the same number of times bigger or smaller than the original or real thing.
Stewie’s foot on the original drawing is ½ inch long.
How long is Stewie’s foot on a 2:1 drawing?
On a 0.5:1 drawing?
If you made a 10:1 scale drawing of the original Stewie, how long would his foot be?

9. Scale
Another way to relate models to actual things is to use a scale, which includes units in different measurements.

10. Use a Proportion to Solve Scale Drawing/Model problems.

11. Practice