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Mapwork

Mapwork and GIS

Grade 12 mapwork uses the contour map, the orthophoto and GIS together to make a decision about a real place.

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Grade 12 · 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 pick a site from the photo alone and ignore the contour that shows a floodplain.

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.

ABN

Diagram

Worked theory

Worked theory. Choosing a site for a small clinic. The contour layer must be flat enough to build. The drainage layer must not be the floodplain. The road layer must reach it. The orthophoto must not show a landfill that the old map omitted. A pretty hilltop that no road reaches fails, even though the view is good. A site in the floodplain fails even though the road is there. GIS is the reason you can refuse both. The worked theory is the refusal, with the layer that caused it.

More worked examples

  • Where not to put the clinic

    Site X is flat, on a tar road, and the orthophoto shows open ground. The contour layer shows it is inside the 1-in-50-year flood line of the river. Site Y is also on the road, 8 m above that line, and the slope layer says it is gentle enough for a single-storey building. X fails on one layer even though it looks perfect on the photo. The decision is Y, and the reason is the flood contour, not the colour of the roof.

  • True bearing 80 degrees

    A line on the map has a true bearing of 80 degrees from north. The magnetic declination for the sheet is 18 degrees west. Magnetic bearing is true bearing plus west declination, so 80 plus 18 is 98 degrees. A compass set to 80 will not walk that line. West declination is added. East declination would be subtracted. Using the wrong sign puts the walker 36 degrees off, which on a 2 km leg is a different hill.

In ordinary words

You still read scale, contours, gradient and intervisibility. GIS adds layers: drainage, slopes, land use, roads. A decision, such as where a road or a settlement should go, is the layers read at once. An orthophoto checks what the symbols mean on the ground. The answer is a place on the map, justified by the layers, not a colouring exercise.

In South Africa

Siting a clinic, a road or a sports field on a local 1:50 000 sheet is the task.

Part 1 / 4

What it is

Grade 12 mapwork uses the contour map, the orthophoto and GIS together to make a decision about a real place.

Diagram
Diagram

More worked examples

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

Example 1 / 20

On a 1 : 10 000 orthophoto, a field is 4 cm long. Calculate its real length.

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: On a 1 : 10 000 orthophoto, a field is 4 cm long. Calculate its real length.

Before any working — hunt first

Given

Numbers and units already in the sentence: 1 · 10 · 000 orthophoto · 4 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: its real length. Circle that word — that is the missing variable.

Find

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

Calculate

What we need to calculate: Multiply. Then substitute the given, one line at a time, to get its real length.

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

If you have never seen this before: Multiply. 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?

4 cm at 1 : 10 000.

3. Which method — and why this one?

Multiply.

4. Step-by-step working

  1. 01 / 08

    Step A — Read the question twice

    Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  2. 02 / 08

    Step A2 — Hunt: Given, Missing, Find, Calculate

    Given: Numbers and units already in the sentence: 1 · 10 · 000 orthophoto · 4 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: its real length. Circle that word — that is the missing variable. Find: We are required to find: its real length. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: Multiply. Then substitute the given, one line at a time, to get its real length.

    Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).

  3. 03 / 08

    Step B — Write the given in a column

    4 cm at 1 : 10 000.

    Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.

  4. 04 / 08

    Step C — Name the method in words

    Multiply.

    Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.

  5. 05 / 08

    Multiply

    4×10 000=40 000 cm=400 m.

    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.

  6. 06 / 08

    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.

  7. 07 / 08

    Step F — Box the answer with its unit

    400 m.

    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.

  8. 08 / 08

    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

400 m.

Copy onto your answer sheet — in this order

Answer: 400 m.

6. Check it like a marker

1 cm=100 m.

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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