Before you leave a question, run four checks on the last line: the unit, the sign, the labels, and whether every part of the task has an answer. It takes about a minute and saves marks you have already earned in the working.
The four-point check
- Unit: is it written, and is it the unit the question asked for?
- Sign: does a positive or negative answer fit the situation?
- Labels: does every quantity say what it is, such as “speed = …”?
- Coverage: has every verb in the question been answered?
Do the check straight after you write the final answer, before you turn the page.
A worked example
A question says: “A student walks 300 m in 5 minutes. Find her average speed in km/h and state whether it is faster than 5 km/h.”
Working: 300 m in 5 minutes is 60 m per minute. In one hour that is 60 × 60 = 3 600 m, which is 3.6 km. Speed = 3.6 km/h.
The unit check confirms km/h was requested and given. The coverage check spots the second task: 3.6 km/h is slower than 5 km/h, so the statement “she walks slower than 5 km/h” completes the answer.
What a weak last line looks like
A common last line is just “60”. The method is right but the unit is missing, and 60 is in metres per minute, not kilometres per hour.
Another weak line is “3.6 km/h” with nothing about the comparison. Both lose marks, even though the working was good.
Signs and sense
Signs need their own look. A length cannot be negative, and a time of −4 s in a motion question means a mistake was made earlier. A negative velocity can be correct if a direction was defined, but only if you can say which way is negative.
Try it yourself
A rectangle measures 12 cm by 5 cm. Find the area, give it in m², and state whether it is greater than 0.01 m².
Answer
Area = 12 × 5 = 60 cm². To convert, 1 m² = 10 000 cm², so 60 cm² = 60 ÷ 10 000 = 0.006 m².
This is less than 0.01 m², which answers the second task. The unit check shows square units were used, and the coverage check shows both the value and the comparison are present.
Next steps
You can practise unit conversions like this one in converting square and cubic units. Use the check together with checking a numerical result with estimation. The hub lists the other habits, and SPM Physics tuition offers one-to-one practice.