Geography · Grades 9–12
Map projections, scale and spatial evidence · revision notes
Representing a curved surface on a plane introduces distortion. Different projections preserve different properties and suit different tasks.
Key ideas and conditions
Projection
Representing a curved surface on a plane introduces distortion. Different projections preserve different properties and suit different tasks.
Scale
A representative fraction compares map distance with ground distance using matching units. Large-scale maps show a smaller area with more detail.
Aggregation
Regional averages can hide within-region variation. Changing boundaries can change summaries even when individual data do not change.
Interpretation
State data date, resolution, legend and missing coverage. A colourful map is not proof of a causal relationship.
Explain without looking
- Explain how changing regional boundaries could alter a choropleth pattern.
- What should missing data look like in a clear map legend?
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