1. Scale Drawings To understands what scale drawings are.
To be able to draw scale drawings
To understand scale drawings.

2. What are scale drawings? Scale drawings are everywhere!
On Maps
Scale Drawings
Vehicle design
Footprints of houses
Can you think of any more?

3. The two shapes are similar
Scale drawings are SIMILAR to the original.
To say that two objects are SIMILAR means that they are identical in shape, but not in size.
In order for two shapes to be similar they must have the same angles and the sides must be in the same ratio.
Example: Are these two shapes similar? x2
Angles the same x2
The two shapes are similar x2
Sides have the same ratio – x2 x2

4. Are these pairs of shapes similar?
3cm
9cm
2cm
6cm
40°
50° 5m 6m 4m
10m 2m 3m 1m
1.5m
50°
60°
70°

5. Understanding scales
All scale drawings must have a scale written on them. Scales are usually expressed as ratios.
Normally for maps and buildings the ratio:
Drawing length: Actual length
For maps the ratio is normally in the ratio:
Map distance: Actual Distance
Example: 1cm : 100cm
The ratio 1cm:100cm means that for every 1cm on the scale drawing the length will be 100cm in real life
Example: 1:10000
The ratio 1:10000 means that the real distance is times the length of one unit on the map or drawing.

6. Writing scale ratios
When you write a scale you must make sure that the units are the same.
Example
Simplify the scale 5cm to 1m
5cm:1m
5cm:100cm
1cm:20cm
Convert to the same units
All ratios must be in the form 1:n.
To make cm 1cm then we must divide each side by 5
Questions – Simplify the following scales
10cm: 2m
5mm:10cm
1cm:1km
1cm:20cm
1mm:20mm
1cm:100000cm

7. Making a scale drawing Task
Make a scale drawing of the building which you are renovating. To do this you need to measure EVERY room and the outside of the building. Do this in metres.
After you have measured the building you need to decide on a scale. Remember the whole drawing needs to fit on an A3 piece of paper.
(I advise you use the scale 1cm:100cm)
Using the scale 1cm:100cm
If a rectangular room measures 2.5m by 4m then you have to convert both of the lengths into cm. (as this is the unit in the scale)
2.5m = 250cm, 4m = 400cm
If 100cm in the actual drawing is represented by 1cm then to get from the actual to the scale you need to divide by 100.
250cm ÷ 100 = 2.5cm 400cm ÷ 100 = 4cm
On the scale drawing this room would be 2.5cm by 4cm