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- More skills: cross-sections, GIS and cumulative frequency
More skills: cross-sections, GIS and cumulative frequency
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The International GCSE also expects you to draw cross-sections, use GIS and work with cumulative frequency and trend lines.
Cross-sections
A cross-section shows the shape of the land along a line on a map.
Lay paper along the line, mark where each contour crosses it and note the height.
Transfer the marks to a graph with height on the vertical axis, then join them with a smooth line.
It shows features such as a V-shaped valley or a steep cliff.
Lay paper along the line, mark where each contour crosses it and note the height.
Transfer the marks to a graph with height on the vertical axis, then join them with a smooth line.
It shows features such as a V-shaped valley or a steep cliff.
GIS
A Geographic Information System stores data in layers on digital maps, such as roads, rivers, population and flood zones.
Layers can be combined to answer questions, for example 'Which homes are on a floodplain?'
Examples include online maps, Google Earth and ArcGIS Online.
Layers can be combined to answer questions, for example 'Which homes are on a floodplain?'
Examples include online maps, Google Earth and ArcGIS Online.
Cumulative frequency and trend lines
Cumulative frequency is a running total. Plot it against the upper end of each class and join the points with a smooth curve.
The median is read at half the total frequency; the quartiles at a quarter and three quarters.
On a scatter graph, a line of best fit (trend line) follows the general pattern of the points, with roughly equal numbers on each side. It can be used to estimate values.
The median is read at half the total frequency; the quartiles at a quarter and three quarters.
On a scatter graph, a line of best fit (trend line) follows the general pattern of the points, with roughly equal numbers on each side. It can be used to estimate values.
Using the table, which class contains the median pebble size?
- Total frequency = 40, so the median is the 20th value.
- The cumulative frequency reaches 20 at the end of the 20 to 40 mm class.
Answer: The 20 to 40 mm class.
Cross-sections show relief along a line using contour heights. GIS layers digital data to analyse places. Cumulative frequency is a running total; read the median at half the total. Lines of best fit show trends on scatter graphs.
The interactive lesson includes the diagrams for this topic.
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