Scale drawings

• Mathematics
• Lower Secondary (Key Stage 3)

Scale drawings

What is a scale drawing?

What is a scale drawing?

• Scale drawings represent real objects with accurate lengths reduced or enlarged by a given
  
• scale
• Scale drawings  are commonly seen as smaller representations of large objects including buildings, gardens and vehicles.
• Scales might be written as a stated scale e.g. 1cm = 1m
• Or as a ratio 1:50
• This means that every 1cm on the plan is worth 50 cm in real-life

Scaling up

• This means we are changing scale measurements to real-life measurements
• So in the scale 2cm = 1m, every 2 cm on the plan is worth 1m (or 100cm) in real-life. 
• Let's take some examples:

2cm = 1m

• The length of a room on a scale plan is 16cm. What would this be in real-life. 
• Answer: 8m
• The width of a room on a scale plan is 7m. What would this be in real-life? 
• Answer: 14cm
• A book shelf is 1.2cm wide on a scale plan. What would this be in real-life?
• Answer: 0.6m
• A playmat is 4cm wide on a scale plan. What would this measurement be in real-life? 
• Answer: 2m 

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Scaling down

• This means we take a real-life or actual measurement and change it to a scale measurement. 
• So in the scale 2cm = 1m, every 2 cm on the plan is worth 1m (or 100cm) in real-life.
  
• Let's take some examples:

2cm=1m

Use this scale to work out what some everyday items would be on the plan. 

• A sand tray which is 70 cm wide
• 70cm= 0.7m (Make sure the cm are converted to metres)
• 0.7 x 2 = 1.4cm (multiply number in m by 2 and this will give the scale measurement).
• A water tray that is 50cm wide
• 50cm = 0.5m
• 0.5x 2 = 1m

How can we change our actual measurements to scale measurements using the scale 2cm=1m?

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Task

Finish your scale drawings from last week

Add only items longer than 50cm. 

How will we work out the actual measurements of the garden?