ZIMSEC O Level · Geography · Form 1, Form 2, Form 3, Form 4
Scale
- Representative fraction: 1 : 50 000 means 1 cm on the map = 50 000 cm (0.5 km) on the ground.
- Linear scale: a line divided into kilometres.
- Real distance = map distance × scale. Measure curved routes with a strip of paper or string.
Worked example: On a 1 : 50 000 map, a road measures 6.4 cm. Find its real length.
6.4 × 50 000 = 320 000 cm = 3.2 km
Grid references
Four-figure references give a square (eastings first, then northings). Six-figure references give a point: estimate tenths within the square. “Along the corridor, then up the stairs.”
Direction and bearing
Use the 16 compass points or bearings measured clockwise from north (000°–360°).
Relief
Contours join places of equal height. Close contours show steep slopes; widely spaced contours show gentle slopes. Spot heights and trigonometrical stations give exact heights. Draw cross-sections by marking contour heights on a strip of paper.
Area
Count full squares and add half the part-squares. Each square on a 1 : 50 000 map is 1 km².
Fieldwork
Plan an aim, collect data (questionnaires, measurements, sketches), present it (graphs, maps) and draw conclusions.
Check yourself
- On a 1 : 25 000 map, two schools are 8 cm apart. How far apart are they?
- What do closely spaced contours show?
- A map square is 2 cm × 2 cm at 1 : 50 000. What area does it represent?
Show answers
- 200 000 cm = 2 km
- A steep slope.
- 1 km × 1 km = 1 km²
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