A legend, or key, explains every symbol, colour and line on a map, along with the scale. To answer a map question reliably, look up the symbol in the legend and quote what it says, instead of relying on memory of other maps.
This lesson builds on grid references and bearings within map reference and direction.
What does the legend give you?
A good legend does three jobs. It names each symbol, so you can tell a road from a track.
It gives the scale, which converts a measurement on paper into a distance on the ground. It gives the contour interval, which converts counted lines into heights.
Colours also carry meaning, but only within the legend. Blue usually means water, though a question may use it differently, so confirm before you write.
Worked example
This map is invented. Its legend says: scale 1:50 000, contour interval 10 m, and a labelled contour of 100 m. A viewpoint symbol is on the third contour line above the 100 m line.
Step 1, height: the lines above 100 m are 110, 120 and 130. The viewpoint is on the third, so its height is 130 m.
Step 2, scale: the viewpoint is 4.6 cm from a car park on the map. At 1:50 000, 1 cm is 500 m.
Step 3, calculate: 4.6 × 500 = 2300 m, which is 2.3 km.
Step 4, check: 4.6 × 0.5 km = 2.3 km. Both routes give the same value, and the answer is a straight-line distance.
The mistake to watch for
The usual error is to assume a symbol or an interval without looking.
Mistaken answer: the viewpoint is 160 m high.
The student assumed a 20 m interval, which would give 100 + 3 × 20 = 160 m. The legend of this map says 10 m, so the height is 130 m.
The correction is to find the interval printed in the legend and write it next to your working. A quick note such as “interval 10 m from legend” also shows the examiner how you got your answer.
Check yourself
Use the same invented legend: scale 1:50 000, interval 10 m, a labelled 100 m contour.
1. A point is on the second line below the 100 m contour. What is its height?
Show answer
Lines below 100 m are 90 and 80. The second is 80 m.
2. Two huts are 7.2 cm apart on the map. Give the straight-line distance in kilometres.
Show answer
7.2 × 500 = 3600 m = 3.6 km.
Check: 7.2 × 0.5 = 3.6 km.
3. A symbol you do not recognise appears on the map. What should you do?
Show answer
Look it up in the legend and quote the entry. If it is not listed, say so in your answer and describe what you can see, rather than guessing a name.
Where this leads next
Next, apply the scale to a longer line in tracing a route without assuming access rights. The mixed practice set includes legend and scale questions.
Students who read the symbols well but drop marks on units can get help from a teacher in online one-to-one Geography tuition.