Sciences Extended Essay structure: sections, criteria and word count

At a glance

The structure, section by section

1. Title page

Required by the IB · Criterion: A (structure) · Outside the word count

Your personal code, the research question, the subject and the word count, plus a statement when explanatory footnotes are counted.

1. Enter your IB personal code.
2. Leave out your name, your supervisor's name, your session number and your school.
3. Paste the research question exactly as it stands in the introduction.
4. Name your science: Biology, Chemistry, Physics or Sports, exercise and health science.
5. Insert the word count from the counter.
6. Add the footnote statement if you used explanatory notes.

2. Acknowledgements or dedication

Common practice (Optional, uncounted and unassessed) · Outside the word count · Only when it applies

Thanks or a dedication with no identifying names.

1. Decide whether you need it.
2. Remove any name that identifies you, your supervisor or your school.
3. Keep it to a few lines.

3. Contents page

Required by the IB · Criterion: A (structure) · Outside the word count

Headings with page numbers.

1. Generate it from your headings.
2. Start page numbers on the page after it.
3. Regenerate it after your last edit.

4. Introduction

Required by the IB · Criterion: A

The research question in its scientific context, with each variable defined, justified and measurable in SI units.

1. State the topic and its scientific context.
2. Write the research question as a question.
3. Define each variable and how you will measure it, in SI units.
4. Say whether you use primary data, secondary data or both.

5. Background and literature review

Required by the IB (A literature review is required in every EE; a separate heading is Convention) · Criterion: A (methods), B

The theory behind the question and what peer-reviewed work already shows.

1. Do your background reading before you design anything.
2. Explain the underlying processes in correct terms.
3. Summarise the most relevant peer-reviewed findings.
4. In Physics, derive the relation you will test.
5. Cut theory the essay will not use.

6. Hypothesis

Common practice · Only when it applies

The expected outcome and its scientific basis.

1. State the expected relationship.
2. Justify it from your background section.

7. Methodology (primary route)

Required by the IB (For primary-data essays, including the primary part of a mixed essay) · Criterion: A · Only when it applies

A replicable method with controlled variables and the dependent variable measured under standardised conditions.

1. List the IV, DV and controls, with how you hold each one constant.
2. List the apparatus with its resolution.
3. Write a procedure someone else could repeat.
4. Report your pilot and what it changed.
5. Add the safety, ethics and environment measures for your investigation.
6. In Chemistry, include the chemical risk assessment and how you dispose of waste.
7. In Biology, describe your sampling design for fieldwork and follow the IB rules for animals and human subjects.

8. Data sources and selection (secondary route)

Rewarded by a criterion (For secondary-data essays, including the secondary part of a mixed essay) · Criterion: A · Only when it applies

The named databases or studies, the selection criteria set in advance, and why their methods are comparable.

1. Name each database or study, with access dates.
2. Set inclusion and exclusion criteria before you search.
3. Check that the sources used comparable methods and controls.
4. Record how you filtered the data.
5. For a systematic review, describe the search strategy and how you selected studies.

9. Participants, consent and welfare (people taking part)

Required by the IB (Required whenever people take part. These details come from the IB's 2015 guidelines and an earlier edition of the guide; the current ethics guidelines are not public, so confirm them with your supervisor) · Criterion: A · Only when it applies

Recruitment, sample and allocation, with consent, anonymity, the right to withdraw and readiness screening.

1. Describe recruitment, sample size and allocation.
2. For an intervention, randomise participants into intervention and control groups.
3. Record written consent, and parent or guardian consent for anyone under 16.
4. Name your screening tool and stop criteria.
5. Keep every result anonymous.

10. Results

Required by the IB · Criterion: A

Data in a standard format with headings, units and numbering, and example calculations that show uncertainties.

1. Tabulate data with headings, units and numbers.
2. Show 1 example calculation per type, with its uncertainty.
3. Plot graphs with error bars.
4. Number every table and figure and refer to it in your text.
5. In Physics, plot a linearised graph with error bars and the maximum and minimum gradient lines.

11. Analysis

Rewarded by a criterion · Criterion: C

Your own processing, statistics where they fit, and any mathematical transformation.

1. Process the data yourself.
2. Apply a statistical test where it fits the data.
3. Transform variables when the theory calls for it.
4. Tie each step to the research question.
5. In Chemistry, propagate uncertainties through your calculations.
6. In Biology, pick the statistical test that suits your data.

12. Discussion and evaluation

Required by the IB (Evaluation must link to the question and the method, and it runs through the essay) · Criterion: D

A critical discussion in scientific context, with the evaluation of method and sources woven in.

1. Interpret your results against the literature.
2. Weigh other explanations.
3. Judge each weakness of method or source where it affects a result.
4. Propose a specific improvement for each one.

13. Conclusion

Required by the IB (Negative results are acceptable) · Criterion: C, D

A synthesis that answers the question and names what remains unresolved and how to address it.

1. Answer the question with your key values.
2. Pull the findings together.
3. State what remains unresolved.
4. Suggest the next investigation.

14. References or bibliography

Required by the IB (Also an academic integrity rule: every source must be acknowledged) · Criterion: A (structure) · Outside the word count

Every source used, in 1 standard style chosen by the school.

1. Use 1 style throughout.
2. List every source you cited, including databases, data booklets, images and AI output.
3. Add URLs and access dates for database and online sources.
4. Check that each in-text citation has an entry.

15. Appendices

Common practice (Optional, and examiners need not read appendices; the signed external mentor form is the one required item) · Outside the word count · Only when it applies

Supporting material only: raw data, long calculations and the mentor form.

1. Include only material the argument can stand without.
2. Refer to each appendix from the body.
3. Insert the signed mentor form if you had a mentor.

16. Reflection sessions log

Required by the IB (The 3 sessions are mandatory and are recorded on the RPF, which is uploaded separately from the essay) · Outside the word count · Submitted separately

The 3 formal reflection sessions, each with its month, your DP year (1 or 2) and your supervisor's initials.

1. After the first reflection session, log its month and your DP year.
2. Log the interim session the same way.
3. Log the viva voce as the third session; it runs 20 to 30 minutes, after your supervisor has read the final version.
4. Ask your supervisor to initial each row; the form carries initials only.
5. If you are retaking, record the current year as DP year 2.
6. Leave informal check-ins off the log.
7. Check that all 3 rows are complete before your supervisor initials and dates the form.

17. RPF reflective statement

Required by the IB (A mandated form, uploaded separately from the essay and marked under criterion E) · Criterion: E · Outside the word count · Submitted separately

Up to 500 words, written after the viva voce, evaluating how the EE shaped you as a learner and which skills you will carry forward.

1. Keep dated notes after each session, ideally in a researcher's reflection space.
2. Reread them after the viva.
3. Evaluate specific decisions and turning points, and keep any account of the process brief.
4. Show how you grew and where you will use the skills.
5. Write every word yourself; an AI-written reflection counts as fabrication.
6. Write in the essay's language and stop at 500 words.

What counts toward the limit

Counted: the introduction, body and conclusion, including quotations and explanatory footnotes or endnotes. Left out: the title page, acknowledgements, contents, page headers, maps, charts, diagrams, annotated illustrations, tables, equations, calculations, citations, reference notes, the bibliography, appendices, the RPF statement and a footnote that gives a quotation's original-language text. The guide does not mention section headings, captions or table titles, so the counter leaves them out as well.

The limit: 4,000 words, plus a 500-word RPF statement. Examiners stop reading at the limit. RPF statement: up to 500 words, counted apart from the rest.

Graphs and visuals

• Tables of processed data Table, very common
  Clearly labelled, with headings, units and numbers; data clearly processed. Tables sit outside the 4,000 words.
• Graphs with error bars Plotted, very common
  Mean bar charts with SD or SE bars and scatter graphs with r or R² (Biology), calibration and kinetics graphs (Chemistry), linearised graphs with max and min gradients (Physics), group-mean bars and pre and post plots (SEHS). Estimates, since no assessed exemplars exist yet.
• Worked calculations and derivations Math, very common
  Example calculations show uncertainties; uncertainty propagation in Chemistry, derivations in Physics.
• Compiled-studies or literature-values table Table, common
  Common in secondary-data essays (an estimate).
• Property against property scatter from compiled literature data Plotted, common
  Common in Chemistry data-based essays; the guide's own example.
• Figures taken from sources Image, occasional
  Allowed with citation, provided the analysis is your own.
• Cross-study comparison chart Plotted, occasional
  An estimate.
• Study-selection flow diagram Drawn, occasional
  Occasional in SEHS systematic reviews (an estimate).
• Summary-of-studies table Table, common
  Common in SEHS systematic reviews (an estimate).

The frequencies are our estimates, from what the IB guide expects and what teachers advise. We did not count them in marked work.

Citations

1 standard style used consistently; the guide sets no science-specific rule. Give access dates for database and online sources, and cite data-booklet and handbook values like any other source. Some study guides suggest APA for science essays.

The workspace keeps your sources and writes the bibliography in APA 7th to start with. You can switch to MLA 9th, Chicago author-date, Chicago notes (footnotes) or Harvard at any point.

Pitfalls

• Choosing a topic that needs equipment your school lacks, or data that would be unethical or impractical to collect.
• Compiling secondary data without your own analysis, or mixing studies whose methods cannot be compared.
• Drifting off the subject or the line of argument, or using methods taken over from a university or company lab.
• Carrying the IA lab report across: reused IA work is barred.
• Adding a stand-alone evaluation after the conclusion, where the guide asks for evaluation throughout.

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Sources

• Extended essay guide, first assessment 2027 (IB; published Feb 2025, updated May, Aug, Nov 2025)
• IB, Extended essay guide, first assessment 2027 (published Feb 2025; updated May, Aug, Nov 2025)
• Extended essay guide, first assessment 2027 (published Feb 2025, updated May 2025 and Aug 2025)
• IB, Extended essay guide, first assessment 2027 (published Feb 2025; updated May, Aug 2025)
• IB, Extended essay guide, first assessment 2018 (published Feb 2016, updated May 2019), including subject-specific guidance
• Guidelines for the use of animals in IB World Schools (IB, ©2015; includes human subjects and secondary data)
• Extended essay guide (earlier edition), SEHS subject details page
• Biology guide, Diploma Programme, first assessment 2025 (published Feb 2023, updated May 2023)
• Physics guide, Diploma Programme, first assessment 2025 (published Feb 2023, updated May 2023)

The IB documents behind this page, checked 29 October 2026. The linked ones are on ibo.org; the others are IB documents we read in copies hosted elsewhere, so we name them without a link. Everything above is in our own words: the official wording is in your subject guide, which your coordinator can give you. LimeAdmissions is independent of the International Baccalaureate Organization, which has not endorsed this page. Every coursework structure →