Dropping IB Biology HL to SL in DP1: What Changes

For M28 students taking IB exams in May 2028 after starting DP1 in August 2026.

If you drop IB Biology HL to SL, you study less content and sit shorter examinations. Your scientific investigation, commonly called the IA, retains the same requirements. Before changing, check your remaining HL subjects, school arrangements, and university prerequisites.

What changes when you drop IB Biology HL to SL?

Both levels follow four themes: unity and diversity, form and function, interaction and interdependence, and continuity and change. HL adds content and expects greater depth and integration.

The official IB Biology overview identifies 150 recommended teaching hours for SL and 240 for HL. This difference affects syllabus coverage, practical work, and lesson time.

Content and depth

SL retains substantial coverage of cells, genetics, ecology, evolution, metabolism, physiology, and molecular biology. You must still interpret data, explain processes, and connect ideas across the syllabus.

You stop studying additional higher level material, including deeper treatment of molecular mechanisms, inheritance, and physiology. Your transition depends on teaching order: some schools integrate HL extensions immediately, while others teach shared material first.

Ask your teacher to identify:

• Completed material that remains examinable at SL
• HL-only material you can stop revising
• SL topics the receiving class has covered that you missed

The RevisionDojo guide to the current Biology syllabus explains the structure, but follow your teacher's M28 course plan.

Examination papers

Both levels take Paper 1 and Paper 2. Paper 1 contains multiple-choice questions in booklet 1A and data-based questions in booklet 1B. Paper 2 includes short-answer and extended-response questions.

Weightings remain 36% for Paper 1, 44% for Paper 2, and 20% for the scientific investigation. SL examinations are shorter and assess only SL content, so switch to level-specific practice rather than judging your progress through HL papers.

The Biology IA

Dropping to SL does not remove your scientific investigation. Both levels use four criteria: research design, data analysis, conclusion, and evaluation, each worth 6 marks.

The investigation retains its 3,000-word maximum and 20% weighting. An HL-style topic is not automatically stronger: choose a focused question supporting reliable data collection and thoughtful evaluation. Use the current Biology IA criteria explanation to avoid following an older rubric.

Workload and lessons

You may enter a separate SL class, leave a combined class during HL lessons, or receive supervised study periods. Released time is not necessarily free time, particularly if another subject must move to HL.

Confirm timetable availability, change deadlines, administrative procedures, and any fees with your DP coordinator before assuming the change is settled.

Check the diploma rules before changing level

Your school must approve the change. Local deadlines, class capacity, and timetable clashes can prevent an otherwise reasonable request.

Under the general IB Diploma Programme curriculum structure, students normally take six subjects and the DP core:

• One subject from each of Groups 1 to 5
• A sixth subject from Group 6, or another from Groups 1 to 5
• At least three and no more than four HL subjects
• TOK, the extended essay, and CAS

Biology satisfies Group 4 at either level. Environmental systems and societies, or ESS, can satisfy both Group 3 and Group 4 requirements, as the IB sciences curriculum page explains. You still need six valid subjects; ESS does not create a five-subject diploma.

If Biology is one of only three HLs, you would normally need to raise another subject to HL. Check its additional workload before agreeing. If you take four HLs, dropping Biology may simply leave the standard three-HL arrangement.

How could the change affect university entry?

The main risk is losing a degree prerequisite. Requirements differ by institution, country, and course, and may change before M28 students apply.

For example, Oxford's Biology requirement specifies Biology and one of Chemistry, Physics, or Mathematics at HL or equivalent. Its Biomedical Sciences course requires two HL subjects from those four subjects.

These examples are not universal rules. Check several realistic universities, record required subjects and grades, and ask your university counsellor to verify your interpretation. Recheck requirements for your intended entry year during DP2.

How to judge whether the change is worthwhile

Compare your complete subject combination before and after the switch, rather than considering Biology alone. Write down your current weekly study commitments, upcoming coursework deadlines, and the subjects most relevant to university entry. The useful question is whether the revised combination makes your overall programme more manageable without closing important options.

For example, a student taking four HLs who does not need Biology HL may gain time for required subjects by moving Biology to SL. A student taking three HLs might gain much less if the replacement HL introduces substantial unfamiliar content. Neither situation guarantees a higher total score, so ask teachers for a realistic assessment of both arrangements.

Look at several marked assignments and tests with your Biology teacher. Separate errors in shared SL content from difficulties with additional HL material, and identify whether incomplete revision or weak examination technique is also contributing. If most lost marks come from shared content, changing level will not address every problem.

Finally, agree on how you will use any released study periods. Allocate specific sessions to catching up on SL topics, practising data interpretation, or meeting deadlines in another subject. Review that plan after a few weeks to check that the change is producing the practical benefit you expected.

What to do during the first week after dropping

1. Obtain written approval. Confirm your coordinator has updated your subject registration plan.
2. Check your diploma structure. Retain six valid subjects and at least three HLs.
3. Collect the SL course plan. Identify missed topics and completed material that remains relevant.
4. Replace study materials. Label notes by level and stop assigning yourself HL-only questions.
5. Confirm your timetable. Check classes, teachers, study periods, and effects on other subjects.
6. Save university requirements. Keep official prerequisite pages for possible degree choices.
7. Review your IA. Confirm that your existing question, method, and schedule remain suitable.

The RevisionDojo Biology coverage guide can help you reorganize notes, questions, and IA resources without restarting the subject.

Common mistakes to avoid

Do not decide from one difficult test alone. Establish whether your difficulty involves knowledge, command terms, data analysis, or revision habits: SL reduces content, not the need for accurate explanations.

Avoid assuming the IA becomes easier, continuing HL-only revision, or postponing university checks until DP2. Treat the change as provisional until your school approves it.

Conclusion

Dropping Biology HL to SL reduces content, examination time, and recommended teaching hours while preserving IA requirements. Check diploma validity and university prerequisites before deciding. Once approved, use RevisionDojo's Biology notes and questions to focus your preparation on SL.

Sources and referenced URLs

• IB Biology curriculum overview
• IB Diploma Programme curriculum
• IB sciences and ESS group coverage
• Oxford Biology course requirements
• Oxford Biomedical Sciences course requirements
• RevisionDojo IB Biology resources
• RevisionDojo current Biology syllabus guide
• RevisionDojo Biology IA criteria guide
• RevisionDojo Biology coverage guide

For your next study session, select SL in the RevisionDojo IB Biology subject hub and compare its topic list with your teacher's course plan.