Percentage is usually met around Secondary 1 — though schools sequence topics differently — and is covered in Odyssey Math Tuition’s online math course for that level, with recorded video lessons, a question bank, topical practice and a topical test. Most marks lost here come from execution errors rather than misunderstanding, which is why targeted practice works.
What percentage actually asks of a student
Percentage work in Secondary 1 covers conversion between percentages, fractions and decimals, percentage increase and decrease, and reverse percentage — finding the original amount after a change.
Reverse percentage is where the topic separates students. It requires understanding that the new value represents a percentage of the original, not the original plus a percentage of itself, and that distinction is the source of nearly all lost marks.
What the topic assumes you already have
Most difficulty in this topic is not caused by the topic itself. It is caused by something earlier that never became fluent. Check these first:
- Fluent conversion between fractions, decimals and percentages
- Multiplying and dividing by decimals confidently
- Setting up a simple equation from a worded statement
- Care with what the percentage is taken of
If any of these is shaky, repair it before going further. Working on new material while a prerequisite is unstable is how students spend hours and move nothing.
Where marks are actually lost
- Applying a percentage to the wrong base — the new value instead of the original
- Treating reverse percentage as subtracting the same percentage back
- Compounding two changes by adding the percentages
- Rounding money to the wrong number of decimal places
- Losing track of whether an answer is a percentage or an amount
Most of these are execution errors rather than gaps in understanding, which is encouraging: they respond to practice and to keeping a written record of the mistakes you personally repeat.
A revision approach that works
- Write, in words, what the percentage is of before calculating anything.
- For reverse percentage, always set the original as the unknown and form an equation.
- Practise successive changes; adding percentages is the standard trap.
- Sense-check: a 20% increase followed by a 20% decrease does not return the original.
How the Secondary 1 course covers it
In the Secondary 1 online course this topic follows the same shape as every other: a recorded explanation, a question bank with answers worked through rather than printed, topical practice, and a topical test. Lessons are recorded personally by our founder, Mr. Justin Tan, and the course follows our own curriculum, aligned to the MOE syllabus.
The courses also include past-year school examination papers with worked answers, which shows how a topic is actually examined rather than how it is taught. Access is 24 hours a day with unlimited replays, and every online course carries a 7-day money-back guarantee.
Where this sits in the wider syllabus
For the year as a whole, see our guide to this stage. For the subject in context, this guide and this one cover what comes before and after.
Syllabus details follow Ministry of Education and SEAB published documents. Course details and prices are as published at the time of writing — check the course pages for current information. We do not promise grades.
Read next
Related reading on studying maths online: Number Patterns: A Secondary 1 Revision Guide, Volume and Surface Area of Prisms and Cylinders: A Sec 1 Guide, Primes, HCF and LCM: A Secondary 1 Revision Guide, Is My Child Actually Learning? Checking an Online Maths Course, Inside the Secondary 3 A-Math Online Math Course. On choosing a school at this stage, see our list of secondary schools in Singapore.
Frequently asked questions
What does percentage cover at Secondary 1?
Percentage work in Secondary 1 covers conversion between percentages, fractions and decimals, percentage increase and decrease, and reverse percentage — finding the original amount after a change.…
What should my child revise before this topic?
The prerequisites listed above. Most difficulty traces back to an earlier skill that never became fluent rather than to the topic itself.
Where do students lose the most marks?
Almost always in execution rather than understanding — sign errors, answering a different question from the one asked, or skipping the sketch.
Is this topic in the online course?
Yes. It is covered in the Secondary 1 online math course with video lessons, a question bank, topical practice and a topical test.
Can we access just this topic?
Yes. The courses are self-paced and non-linear, so a student can go straight to one topic without working through the rest.
Is there a trial period?
All online courses carry a 7-day money-back guarantee. The terms and conditions set out how it works.
Last reviewed July 2026. Syllabus details follow the Ministry of Education and SEAB published documents.
