Estimating lengths from scale drawings and photos

Task goals

• Understand that a scale of 1:n means 1 unit on the drawing or photo represents n of the same unit in real life, and convert both lengths to the same unit before scaling.
• Given a scale ratio 1:n and a real-world length in metres, find the corresponding model or drawing length in centimetres.
• Given a scale drawing's length in centimetres and its scale ratio 1:n, find the real length in metres.
• Given a map's scale ratio 1:n and a distance measured on the map in centimetres, find the real distance in kilometres.