Balancing a session means deciding how many questions each science gets before you open any book, using the topic list for your actual route. It matters whenever you practise across biology, chemistry and physics in one sitting, and it is the first habit in double-award practice design.
How do I split a session fairly?
Start from your checked scope, then let numbers, not mood, decide.
- Build the grid. From the current Cambridge syllabus for your entry, list the topics under biology, chemistry and physics. Count them for each science.
- Fix the session size. For example, 12 questions or 60 minutes.
- Share by topic count. Questions for a science = session size × (its topics ÷ all topics).
- Round to whole questions so the total stays the same.
- Adjust once for weakness. Move one question towards the science with the most recent errors in your mistake log.
Worked example (invented data)
Aisha’s checked topic list has 9 biology topics, 6 chemistry topics and 5 physics topics. She plans a 10-question session.
Total topics = 9 + 6 + 5 = 20.
- Biology: 10 × 9/20 = 4.5
- Chemistry: 10 × 6/20 = 3.0
- Physics: 10 × 5/20 = 2.5
The decimals add to 10 but cannot be set as questions. Chemistry is exact at 3. Biology and physics each have a half, so one rounds up and one rounds down.
Her last mistake log shows more physics errors, so physics gets 3 and biology gets 4.
Plan: biology 4, chemistry 3, physics 3. Total 10. Re-check: 4 + 3 + 3 = 10, and each share is within one question of its exact value.
The mistake to watch for
A student plans by feeling instead of counting.
Mistaken plan (12 questions): biology 2, chemistry 2, physics 8, because physics homework is due.
This is a good plan for tonight’s homework and a poor plan for coverage. After four such sessions, biology and chemistry have almost no practice.
The correction is to run the count first, then change one question for a real reason such as a deadline. If homework in one science is due, do it as separate work and keep the practice session balanced.
Check yourself
All counts are invented.
1. A checked list has 15 biology, 10 chemistry and 5 physics topics. Share a 12-question session.
Show answer
Total = 30. Biology 12 × 15/30 = 6; chemistry 12 × 10/30 = 4; physics 12 × 5/30 = 2. 6, 4, 2, which adds to 12.
2. A list has 7 biology, 7 chemistry and 6 physics topics. Share a 10-question session.
Show answer
Total = 20. Biology 10 × 7/20 = 3.5; chemistry 3.5; physics 10 × 6/20 = 3.0. Physics is exact at 3. The two halves split into 4 and 3. For example biology 4, chemistry 3, physics 3, giving the extra question to whichever science your log shows more errors in.
3. You planned 5, 5, 5 for a 15-question session, but your log shows most recent errors in chemistry. Give a sensible adjusted plan and say why it is still balanced.
Show answer
Move one question to chemistry: for example biology 4, chemistry 6, physics 5. The total is still 15 and no science has fewer than 4 questions, so coverage stays broad while chemistry gets extra attention.
Where this leads next
Once the split is set, decide what kinds of question go inside each share in mixing recall, interpretation and application tasks. The mistake log and retest queue helps you record which science needs the extra question, and the module practice set lets you try these plans.
If you would rather have someone else read your topic list and spot gaps, our teachers can do that in online one-to-one Co-ordinated Sciences tuition.