Mapwork

Mapwork and GIS

Mapwork is reading a real landscape from a 1:50 000 topographic map, an orthophoto and, later, GIS layers.

CAPS

Grade 10 · Geography · Mapwork

Geography examines physical and human processes, with map skills in both papers.

The papers
Paper 1 is climate and weather, and geomorphology, with geographical skills. Paper 2 is rural and urban settlement, and the economic geography of South Africa, with geographical skills. Each paper is 150 marks.
Map work
Direction, scale, gradient, cross-section and a calculation from the map must show the formula and the substitution. A place you cannot point to on the extract is a guess.
How a marker reads it
A common mix-up is to treat contour numbers as rainfall, or to ignore the scale and call a 2 cm road “2 cm long” on the ground.

Paragraph questions want causes and effects in sequence. Naming a term without saying how it changes the landscape or the settlement is only the first mark.

Diagram

Worked theory

Worked theory. A hiking slope in the Magaliesberg drawn with contours every 20 m. Where four contours pack into a few millimetres, the slope is a cliff and a path should not go straight up it. A river must cross contours in a V that points upstream. If your V points the wrong way, the river is flowing uphill on your reading, which is the sign to turn the interpretation around. An orthophoto of the same slope shows the real vegetation and houses the contour map only symbols. GIS lets you see the path, the river and the height at once. The skill is the landscape, not the colouring-in.

More worked examples

4 cm on a 1:50 000 sheet
A footpath measures 4 cm on the map. The scale says 1 cm is 500 m, so the walk is 2 km, not 4 cm and not 4 km. Contours along it are 20 m apart and packed tight for the first kilometre: a steep start. They space out after that: the path levels. A V in the contours points upstream, toward the packed lines, so the stream is flowing the other way, off the slope. The orthophoto of the same square shows the trees the brown lines cannot.
A six-figure grid reference
A bridge sits in grid square 3218. It is about 4 tenths of the way across the square and 7 tenths of the way up. The six-figure reference is 324187: the third digit is the tenths easting, the sixth is the tenths northing. Writing 3218 names the whole square, which is a kilometre on a 1:50 000 sheet, not the bridge. Reading the tenths upwards first swaps the numbers and puts the point in the wrong field.

In ordinary words

The scale 1:50 000 means 1 cm on the map is 50 000 cm, which is 500 m, on the ground. Contours are lines of equal height. When they are close, the slope is steep. The map’s north is not always the direction you are facing, so you set the map. Conventional signs show roads, rivers, buildings and vegetation. An orthophoto is a photograph corrected so distances stay true. GIS is those layers, stored so you can turn roads, rivers and contours on and off together.

In South Africa

A South African 1:50 000 sheet of your own district is the map this skill is for.

Part 1 / 4

What it is

Mapwork is reading a real landscape from a 1:50 000 topographic map, an orthophoto and, later, GIS layers.

Mapwork and GIS / topo-map-legend-sa — Diagram

1:50 000 topographic map legend — Diagram

Mapwork: intervisibility and gradient — Diagram

More worked examples

Board walkthroughs on this topic. Open one, copy the working, then try the next.

Example 1 / 20

A map has a scale of 1 : 50 000. Two points are 4,2 cm apart. Calculate the real distance in km.

4. Step-by-step working

01
Multiply
4,2×50 000=210 000 cm.
02
Convert units
210 000 cm=2,1 km.

How we got there

Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.

Explain in another language · 11

1. What is the question asking?

Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A map has a scale of 1 : 50 000. Two points are 4,2 cm apart. Calculate the real distance in km.

Before any working — hunt first

Given

Numbers and units already in the sentence: 1 · 50 · 000 · 4,2 cm. Copy each one into a column. A name without a number is not given.

Missing

After you copy the given, the letter that still has no number is missing. The paper is pointing at: the real distance in km. Circle that word — that is the missing variable.

Find

We are required to find: the real distance in km. Write that as a symbol on the left, with a question mark, before you touch a formula.

Calculate

What we need to calculate: Distance = map × scale. Then substitute the given, one line at a time, to get the real distance in km.

In other words — as if you have never seen this before

If you have never seen this before: Distance = map × scale. We will name a method in words, write the formula with no numbers, then substitute one line at a time.

2. What do we already know?

Scale 1 : 50 000; 4,2 cm.

3. Which method — and why this one?

Distance=map×scale.

4. Step-by-step working

01 / 05
Multiply
4,2×50 000=210 000 cm.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
02 / 05
Convert units
210 000 cm=2,1 km.
Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
03 / 05
Step G — Sense-check the size
Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
04 / 05
Step F — Box the answer with its unit
2,1 km.
Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
05 / 05
Step H — What the marker is looking for
On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.

5. The answer

2,1 km.

Copy onto your answer sheet — in this order

Answer: 2,1 km.

6. Check it like a marker

1 cm=0,5 km.

7. A trap first-timers fall into

First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”

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