# Grade 9 Geography Mapping Skills - PowerPoint PPT Presentation

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## Grade 9 Geography Mapping Skills

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### Grade 9 GeographyMapping Skills Map Scale. Maps are very useful tools for locating things, determining direction or calculating distances. What? – PowerPoint PPT presentation

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Title: Grade 9 Geography Mapping Skills

1
Grade 9 Geography Mapping Skills Map Scale
• Maps are very useful tools for locating things,
determining direction or calculating distances.
• What? How do you calculate a real or actual
distance from a paper map?

2
Grade 9 Geography Mapping Skills Map Scale
• Calculating real distances
• You need two things from your map AND a
mathematical formula to determine real distances
• Map Distance The measured distance on the map
• Scale A ratio (i.e., each centimetre on the map
is how far in real life
• Formula MD/GD scale where GD is Ground
Distance (the real or actual distance)

3
Grade 9 Geography Mapping Skills Map Scale
• Map Distance (MD)
• With a ruler, you need to measure the distance ON
THE MAP from your starting point to your
finishing point.
• The example shows a trip starting in Istanbul and
finishing near the border with Iran. With a
ruler, measure the line. This is the distance on
the map or Map Distance (MD)

4
Grade 9 Geography Mapping Skills Map Scale
• Scale
• Scale is located on the mapusually along a
bottom edge
• Scale is a statement of the relationship between
distances on a map (i.e., Map Distance (MD)) and
distances in real life (i.e., Ground Distance
(GD)).
• As you know, a drawing made according to the
scale will be an exact copy of the real
objectonly smaller.
• Scale is always presented as a ratio on a map.
For example, scale is given as 125,000,000 which
means 1 cm on a map is 25,000,000 cm in real life
(or 250 km)

5
Grade 9 Geography Mapping Skills Map Scale
• Formula
• The formula for calculating the real distance
(i.e., Ground Distance (GD)) is a ratio.
• If you know Map Distance (MD) and scale, you can
somehow combine them to calculate GD.

MD / GD scale
6
Grade 9 Geography Mapping Skills Map Scale
MD / GD scale
• Example
• Scale is 137,000,000 or 1 cm 370 km or 1 / 370
• MD 10.2 cm
• What is Ground Distance (GD)?
• MD / GD 1 / 370
• Let GD x
• 10.2 / x 1 / 370
• x (10.2)(370) 3,374
• The Ground Distance is 3,374 km

7
Grade 9 Geography Mapping Skills Map Scale
MD / GD scale
• Try one
• Scale is 125,000,000 or 1 cm 250 km or 1 / 250
• MD 13.2 cm
• What is Ground Distance (GD)?
• MD / GD 1 / 250
• Let GD x
• The Ground Distance is 3,300 km right?