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 taxi from Gqeberha covers 160 km in 2 h. Average speed?
Before any working — hunt first
Given
Numbers and units already in the sentence: 160 km · 2 h. 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: Average speed. Circle that word — that is the missing variable.
Find
We are required to find: Average speed. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
Write v = Δx / Δt with empty letters. Cross out every letter that already has a number. Calculate the letter that is still standing — that gives Average speed.
In other words — as if you have never seen this before
Average speed is total distance over total time. Do not invent acceleration — the paper did not give it.
2. What do we already know?
Δx = 160 km. Δt = 2 h. Unknown: average speed v.
3. Which method — and why this one?
Average speed is total distance over total time. Do not invent acceleration — the paper did not give it.
4. Step-by-step working
01 / 05
Write the definition
v=Δx / Δt. Distance over time, units kmh.
v=ΔxΔtWhy this step: Write the formula before numbers. The memo awards a method mark even if a digit slips later.
02 / 05
Substitute
v=1602=80 kmh.
v=80 kmhWhy this step: One job per line so you can find a slip, and so a marker can follow the marks.
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
80 kmh
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
80 kmh
Copy onto your answer sheet — in this order
Formula: v=ΔxΔt
Answer: 80 kmh
6. Check it like a marker
80 kmh × 2 h = 160 km. Recovers the given distance.
7. A trap first-timers fall into
Do not multiply 160 × 2. Speed is not distance times time.