To calculate the area of a regular shape on an OS map extract: 1. Count the number of squares along the bottom of the map. 2. Count the number of squares along the side of the map.
3. To calculate the area, multiply your answers from step 1 and step 2 to get the area in km2
. Irregular Shape
To calculate the area of an irregular shape on an OS map extract:
1. Count the number of squares fully covered (tick them as you go along so you do not count them twice by mistake).
2. Count the number of squares more than half covered. Ignore squares that are less than half covered.
3. Add your answers from step 1 and step 2 to get the area in km2
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: Fig. 14.14 Calculating area of an irregular shape Skill 10: Sketch Mapping
Drawing an accurate sketch map requires a great deal of care. Although many students attempt to draw sketch maps in the exam, they often make careless mistakes that can be avoided by applying these rules:
• Turn the map extract until the north arrow is pointing upwards. This will give you the correct orientation for the map.
• Draw the frame of your map to half-scale. This can be done in three ways:
1. Measure the width and length of the map with your ruler and divide both by 2.
2. Count the number of squares along the width and the side. Let each square equal 1 cm (normally each square is 2 cm).
3. Let each half square of your graph paper represent a full square of the map. If you do this then you can use the graph squares to guide you while inserting the features.
GEO DICTIONARY
Orientation: in relation to a map, whether it is landscape
or portrait
Half-scale: drawing a map to half of its original size
