Calculate map and real distances in simple problems.
Form 1โ๏ธ Worked examples๐ฎ Interactive learning
1 cm โ real life
๐ฏ Learning Objectives
By the end of this lesson, you should be able to:
Find real distance from map distance.
Find map distance from real distance.
Choose multiplication or division correctly.
Solve route problems containing more than one section.
๐ค Start with the Idea
Scale questions may ask for the real distance or the map distance. The direction of the calculation tells us whether to multiply or divide.
๐ Choose the Correct Operation
Map โ Real
Multiply by the distance represented by 1 cm.
real = map ร scale value
Real โ Map
Divide by the distance represented by 1 cm.
map = real รท scale value
๐ฎ Explore the Scale
Change the map or drawing length and the scale value. Notice how the real distance changes proportionally.
๐ง Letโs Think Together
A 72 km road is shown on a map with scale 1 cm represents 8 km. Find its map length.
We are moving from real distance to map distance, so divide.
72 รท 8 = 9 cm
Answer: 9 cm.
โ๏ธ Practice Questions
Build confidence
Scale 1 cm = 6 km. Find the real distance for 7.5 cm.
Scale 1 cm = 15 km. Find the map distance for 120 km.
A route has map sections 3 cm, 4.5 cm and 2 cm at 1 cm = 8 km. Find the full real route.
โ Check your answers
45 km
8 cm
76 km
โ ๏ธ Common Mistakes
Using different units on the two sides of a ratio scale.
Multiplying when the question requires division, or dividing when it requires multiplication.
Leaving out the unit or using a linear unit for an area.
Rounding too early in a multi-step calculation.
๐ฏ Exam Focus
Write what the scale means before calculating. Show unit conversions clearly, keep full calculator values until the final step, and include the correct unit in the answer.
๐ One-Minute Summary
A scale connects a drawing or model to the corresponding real object.
Use multiplication when moving from a drawing measurement to a real measurement.
Use division when working backwards from real size to drawing size.
Ratio scales require the same unit on both sides.
Area changes by the square of the linear scale factor.