These constructed examples show how an explanation can move beyond giving the answer. They illustrate particular Cambridge syllabus skills; a tutor should choose tasks from the learner’s own course.
Maths: why adding the discount back gives the wrong price
A jacket costs £64 after a 20% discount. If its original price was £80, the sale price is £80 × 0.8 = £64: the buyer pays 80% of the original. Working backwards, £64 is therefore 80%, so the original is £64 ÷ 0.8 = £80. Adding 20% of £64 instead gives £76.80 because it uses the smaller sale price as the starting amount.
For Cambridge Mathematics 0580 in 2025–27, percentage decrease is Core content and finding the original amount is an Extended skill. For further reverse-percentage practice, a £90 sale price after a 25% discount means £90 ÷ 0.75 = £120 originally. A useful sign of understanding is explaining why the divisor is 0.75.
English: explain the effect of a word choice
Take the invented sentence, “The corridor swallowed her footsteps.” Saying “this is personification” identifies a device but leaves its effect unexplained. A fuller response could be: “The verb ‘swallowed’ makes the corridor seem powerful, as though it absorbs every sound and leaves her isolated.” That interpretation connects a selected word to an impression; in a real passage, the surrounding details must support it.
Cambridge First Language English 0500 in 2027–29 includes explaining how writers achieve effects. Practise this by choosing a short quotation from the learner’s set passage and explaining what its particular words suggest, rather than attaching the same comment to every technique.
Chemistry: faster gas collection does not prove a bigger final yield
Suppose two experiments measure gas collected from a reaction under the same measurement conditions, both starting at 0 cm³. After 10 seconds, experiment A has collected 20 cm³ and B has collected 10 cm³. Their average rates over that interval are 20 ÷ 10 = 2 cm³/s and 10 ÷ 10 = 1 cm³/s. A is faster over those first 10 seconds. That does not establish which experiment will produce more gas in total: the final volumes are needed.
Cambridge Chemistry 0620 in 2026–28 includes interpreting rate-of-reaction data and graphs. When comparing graph lines, distinguish the slope, which shows how quickly gas accumulates, from the final height, which shows the volume collected. In a fair test, keep other relevant conditions the same when changing the factor being investigated.
For this chemistry course, the Alternative to Practical paper still requires experimental skills. Discuss how the learner will gain practical experience as well as preparing for written questions.
