This document discusses scale factors and drawing to scale when creating architectural plans. It explains that scale factors are used to reduce or enlarge shapes proportionally so they can fit on a page. Architects use scales like 1:20 or 1:100, where 1cm on the drawing represents 20cm or 100cm in real life. This allows them to accurately draw floor plans and show the relative sizes of rooms, doors, windows, and other features in a building design. Examples are provided for how to determine real-life sizes from measurements on drawings using different scale factors.

1. Architect Plans
 If you had to draw the table you are sitting at
on a sheet of A4 paper, how would you do it?
 You would make it smaller? How much
smaller?
 We have to make it proportionally smaller?
Why?
 We have to reduce it by a scale factor? What
does that mean?

2. Scale factors
 When we draw maps or plans
we use a scale so that we can
fit a large area on a small
amount of paper. Making a
life-size drawing would
perhaps be more accurate but
perhaps a little impractical.
 What a scale factor does is
reduce or enlarge a shape
such that while it is made
bigger or smaller, its
proportions remain the same.

3. Enlarging by a scale factor
 The size is increased
 Proportionally equal

4. Drawing to Scale
 When architects draw up plans they use a scale, for example 1:20
 This means that 1cm on the drawing represents 20cm in real life
 Why do they do this?
 Drawing to scale is easy!
 If using a scale of 1:100 that means that 1cm on the drawing would
represent 100cm (1m) in real life
 If I therefore wanted to draw my bed, for example, and the bed was
200cm x 150cm (2m x 1.5m) then how big would I draw the bed on
my plans?
 That’s right – I would draw it 2cm by 1.5 cm

5. How about different scales?
 This rectangle is 2cm by 4cm
 If the scale were 1:20 then how big would the rectangle be?
 For every 1cm on the drawing we have to count 20cm in real life
 20 x 4cm = 80cm
 20 x 2cm = 40cm
 How big would it be in real life if the scale were 1:100?
 What about if the scale were 1:50?
 How about 1:10?
2cm
4cm

6. Making plans
 Scales allow architects to draw accurate
floor plans for their buildings
Double-glazed windows
door