Home › Subjects › O-Level Combined Science
O-Level Combined Science revision: concepts, calculations and practice
Secondary school, working toward the Singapore-Cambridge GCE O-Level. Rae explains, marks and drills Combined Science with your level in mind. Free to try, no install.
Choose your combination first: Physics/Chemistry (5086), Physics/Biology (5087) or Chemistry/Biology (5088). The calculation lessons below practise overlapping foundations; the linked topic pages also contain Pure Science material, so check the scope of your own combination.
Start with a complete lesson
Energy calculations: work, kinetic energy and efficiency
Two worked examples, an independent question and common mistakes.
DC circuits: series and parallel resistance with worked answers
Two worked examples, an independent question and common mistakes.
Chemical calculations: moles, reacting masses and concentration
Two worked examples, an independent question and common mistakes.
Acids, bases and salts: neutralisation and choosing a preparation method
Two worked examples, an independent question and common mistakes.
A revision routine you can repeat
- For physics, name the quantity, choose the equation and convert units before substitution.
- For chemistry, write a balanced equation and move through moles before converting to mass or concentration.
- For explanation questions, connect a cause to an observable effect. Check practical skills against your school guidance; reading worked answers does not replace laboratory practice.
Scope: Combined Science 5086, 5087 and 5088, examination year 2026. Check the official syllabus. For 2027 SEC, check your school’s G3 syllabus; do not assume the examination label and code stay the same.
Print the Combined Science: units and calculations practice sheet
What Rae does for Science
- Explanations with references where available; check important facts against your course materials.
- Processes and cycles drawn as clear diagrams.
- Explanations pitched at your level, from first principles up.
- Snap a photo of the problem, send a voice note, or attach the file.
- Revisit topics with Rae’s notes and practice tools.
Tell Rae your O-Level subject and syllabus, then check the explanation against your course materials.
How it works
Open Rae on the web or in Telegram. Ask a question, attach your working or use voice. Read the explanation, try a follow-up question and use the notes and practice tools to revisit what you learned. AI feedback can make mistakes; check it against your syllabus and your teacher’s guidance.