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 learner mixes sand with iron filings. Classify the mixture, and name one physical method that separates the iron.
In other words — as if you have never seen this before
If you have never seen this before: If you can still see the pieces, the mixture is heterogeneous. A magnet pulls iron and leaves the sand. No new substance forms. 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?
Sand and iron filings, still visible as two materials.
3. Which method — and why this one?
If you can still see the pieces, the mixture is heterogeneous. A magnet pulls iron and leaves the sand. No new substance forms.
4. Step-by-step working
01 / 05
Identify the given
Two materials remain visible. That is not one phase.
heterogeneous mixtureWhy 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
Apply the law
Iron is magnetic. Sand is not. A magnet removes the filings.
magnetWhy 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
Sense-check
The sand and the iron are unchanged. Dissolving or a reaction was not needed.
physical separationWhy 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.
04 / 05
Step F — Box the answer with its unit
Heterogeneous mixture. Separate the iron with a magnet.
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
Heterogeneous mixture. Separate the iron with a magnet.
Copy onto your answer sheet — in this order
Formula: heterogeneous mixture
Answer: Heterogeneous mixture. Separate the iron with a magnet.
6. Check it like a marker
A solution, such as salt in water, is homogeneous. You cannot pick the salt out with a magnet.
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…”