Ratio, proportion & rates of change · Ratio
Chapter 1 · 3
The idea
Scale drawings and map scales (1 cm represents…, 1 : n)
Turn a length on a map or scale drawing into a real length and back again: use a scale written as "1 cm represents 5 km", as a scale bar or as a ratio 1 : n, change the units inside a ratio scale, write any scale in the form 1 : n, follow a route instead of a straight line, measure and draw to scale, and scale an area by the square of the scale.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Ratio, proportion & rates of change · Ratio
Scale drawings and map scales (1 cm represents…, 1 : n)
Turn a length on a map or scale drawing into a real length and back again: use a scale written as "1 cm represents 5 km", as a scale bar or as a ratio 1 : n, change the units inside a ratio scale, write any scale in the form 1 : n, follow a route instead of a straight line, measure and draw to scale, and scale an area by the square of the scale.
Why it works
A map is the world shrunk
Priya is planning a bike ride from Penwick to the lighthouse at Tolsey Head. On her map the two places are cm apart. How far will she ride?A map is the real world shrunk by the same amount in every direction, and its scale says by how much. Priya's map says " cm represents km": every centimetre on the map stands for km on the ground. So cm stands for km. A plan of a room and a model car work the same way. We will follow Priya's map all the way down this page.Keep reading — free
The rest of the explanation, plus 5 worked examples you step through move by move.
Start freeTakes a minute — no card.