Map skills
- Grid references give eastings (along the corridor) first, then northings (up the stairs). A four-figure reference gives a grid square; a six-figure reference gives a point to the nearest tenth of a square.
- Scale: on a 1:50,000 map, 2 cm represents 1 km; on a 1:25,000 map, 4 cm represents 1 km.
- Contour lines join points of equal height. Lines close together mean steep land; lines far apart mean gentle slopes. Spot heights and triangulation pillars show exact heights.
- Use the eight points of the compass: N, NE, E, SE, S, SW, W and NW.
- To describe a distribution, say where things are, give examples and mention any anomalies.
Graphs and maps
- Line graphs show change over time; bar charts compare categories; pie charts show proportions; scatter graphs show relationships (correlation); population pyramids show the age and sex structure of a population.
- Choropleth maps shade areas according to their values, with darker shades for higher values. Flow lines show movement, with thicker lines for more movement. Proportional symbols are sized according to their values. Isolines join points of equal value, such as contour lines.
Numbers and statistics
- Mean, median, mode and range. The interquartile range is the upper quartile minus the lower quartile.
- Percentage change = (new value − original value) ÷ original value × 100. A rise from 40 to 50 is a 25% increase.
- When describing data, quote figures, compare the highest and lowest values, and describe trends.
Using photographs and images
- Describe what you can see (land use, landforms, buildings and people), and use this evidence to support your answers. Satellite images show large areas and change over time.
Key terms
- Grid reference
- A set of numbers that gives a location on a map.
- Easting
- A vertical grid line, numbered along the map; read first in a grid reference.
- Northing
- A horizontal grid line, numbered up the map; read second in a grid reference.
- Contour line
- A line on a map joining points of equal height.
- Scale
- The ratio between distances on a map and real distances.
- Choropleth map
- A map with areas shaded according to their values.
- Isoline
- A line on a map joining points of equal value.
- Population pyramid
- A graph showing the age and sex structure of a population.
- Interquartile range
- The upper quartile minus the lower quartile.
- Correlation
- A relationship between two variables.