Extended Essay Criterion B: Knowledge and Understanding

By Michael Thompson · Education Specialist; 10 years teaching the IB at Bromsgrove School · Published 4 October 2026

Extended essay criterion B - Knowledge and Understanding - is one of five criteria used to assess the new extended essay from May 2027, and it carries 6 of the available 30 marks. The guiding question examiners use is: 'Does the student demonstrate knowledge and understanding of the subject matter being used in their research?' That sounds broad, but it has a specific focus: whether you use subject terminology accurately, understand the research methods you have chosen, and show genuine command of the concepts relevant to your research question. This guide explains what that looks like in practice, where drafts typically fall short, and how this criterion connects to the other four so you do not optimise for it in isolation.

Key Takeaways

• Criterion B is worth 6 marks out of 30: It sits within a five-criterion framework introduced in February 2025 for first assessment in May 2027.
• The guiding question is specific: Examiners ask whether you demonstrate knowledge and understanding of the subject matter being used in your research - not general knowledge of the topic area.
• Accurate terminology matters more than volume: Using subject-specific terms correctly and consistently throughout the essay counts more than citing many sources or writing lengthy background sections.
• Understand your methods, not just your results: The IB's 'know and understand' assessment objective includes relevant research methods, so show you understand the methods you used; whether they suit your question is part of Criterion A's framework.
• Interdisciplinary pathway students must show knowledge of both subjects: If you follow the interdisciplinary pathway, criterion B applies across the two DP subject lenses you have integrated.
• No grade boundaries exist yet for the 30-mark scale: The IB will set boundaries after the May 2027 session; results are due 6 July 2027.

In This Article

1. What the 2027 Extended Essay Assessment Model Looks Like
2. Extended Essay Criterion B: What It Actually Assesses
3. Knowledge and Understanding Across Subjects and Pathways
4. How to Demonstrate Knowledge and Understanding in Your Draft
5. Common Ways Drafts Fall Short on This Criterion
6. How Criterion B Connects to the Other Four Extended Essay Criteria
7. What to Do This Week

1. What the 2027 Extended Essay Assessment Model Looks Like

Extended essay criterion B sits within a new five-criterion assessment model that applies to every student sitting the IB Diploma Programme Extended Essay from May 2027 onwards. The new EE guide launched in February 2025, replacing the previous 34-mark framework entirely.

> Transition note: November 2026 is the last examination session assessed on the old 34-mark model. From May 2027, all EEs are marked on the 30-mark scale described below. The criteria, criterion names, and weighting described in this article apply only to the 2027 model.

The five criteria and their mark allocations

Per the IB's extended essay updates page, the assessment model is:

Criterion D carries the highest mark allocation at 8 out of 30, making it the most heavily weighted single criterion. Criterion E carries the lowest at 4 marks.

One feature of the new model worth noticing: A, B and C each carry the same 6-mark maximum, but D carries 8, so B and D together account for nearly half the total available marks. A student who focuses only on research depth without attending to discussion and evaluation is working against the weighting.

The Extended Essay still combines with Theory of Knowledge for a maximum of 3 diploma points. No grade boundaries have been set for the 30-mark scale. The IB will set those as part of the May 2027 session, and results are released on 6 July 2027.

2. Extended Essay Criterion B: What It Actually Assesses

Criterion B is titled "Knowledge and Understanding." Its guiding question, drawn directly from the IB Diploma Programme Subject Brief for the Extended Essay (first assessment 2027), is: "Does the student demonstrate knowledge and understanding of the subject matter being used in their research?"

It is worth 6 marks out of a total of 30 across the five criteria.

What the criterion actually assesses lines up most closely with the subject brief's 'know and understand' assessment objective: know and understand the topic and research question, the relevant terminology and concepts, and the research methods appropriate to the investigation. That last element, research methods, catches students off guard. It is not enough to know the subject content. You also need to show that you understand the methods you used; the case for why they suit your question is part of Criterion A's framework.

The criterion rewards accuracy and relevance, not volume. A lengthy background section that covers everything a reader might want to know about your general topic does not satisfy extended essay criterion b. Neither does a wall of quotation. What examiners are looking for is your own articulation of ideas, in the discipline's own language, held in direct relationship with the research question.

Two practical consequences follow from this:

• Define key terms once, clearly, then use them consistently. Terms dropped into the text without definition, or defined and then abandoned, signal that the student has not yet internalised the concept.
• Every paragraph should pull toward the research question. Context belongs in the essay only when it directly helps answer that question. Background included for its own sake dilutes the demonstration of focused understanding.

The counter-intuitive implication: a tightly argued 3,500-word essay that stays anchored to its question can outscore a 4,000-word essay that front-loads three pages of general subject history. Demonstrating knowledge in an extended essay is about signal, not mass.

3. Knowledge and Understanding Across Subjects and Pathways

Both research pathways in the 2027 EE model, subject-focused and interdisciplinary, are assessed against the same five criteria. Extended Essay Criterion B applies equally to either route; the pathway you choose changes what knowledge you must demonstrate, not whether it is assessed.

The most demanding version of Criterion B sits inside the interdisciplinary pathway. This route, which has also absorbed the former world studies EE, integrates the lenses of two DP subjects, so students must show fluency in both disciplines. Demonstrating knowledge of only one subject while gesturing at the other leaves an obvious gap under this criterion.

For language A and language B essays, the IB has removed the old categories. Criterion B still requires accurate, subject-appropriate knowledge and understanding of the texts, language or culture you are researching.

Regardless of subject, three things define what the criterion is actually looking for:

• Accurate use of subject-specific terminology, applied consistently rather than listed once in a glossary and forgotten.
• Understanding of the research methods chosen, including what they can and cannot show, not just what was done.
• Command of relevant concepts, used to build argument rather than to fill background sections.

In practice, this looks different across disciplines:

• Biology - a student explaining why a controlled experiment was chosen over a correlational design, and what variables were isolated, signals genuine methodological understanding.
• History - distinguishing between primary source types (a government dispatch versus a personal diary) and explaining what each can and cannot tell you shows conceptual command.
• Language B - analysing how a particular sociolinguistic concept, such as code-switching, operates in the chosen texts demonstrates the cultural and linguistic knowledge the criterion requires.

The counter-intuitive point: Criterion B is not rewarding the volume of subject knowledge you have accumulated. It rewards the knowledge you deploy in direct service of your research question.

4. How to Demonstrate Knowledge and Understanding in Your Draft

The IB EE subject brief states that demonstrating knowledge and understanding means knowing your topic and research question, using terminology and concepts accurately, and understanding the research methods you apply. Those three elements translate into specific writing habits.

Define a term once, then use it with confidence. If your biology EE introduces "enzyme-substrate specificity" in the introduction, you do not need to gloss it again in the analysis. Redefining the same term signals uncertainty rather than mastery. Equally, avoiding subject-specific language to sound "safer" costs marks: examiners can tell the difference between a student writing around a concept and one who owns it.

Show the reasoning behind your method, not just the outcome. If you used a semi-structured interview rather than a survey, say why: what did that method allow you to find, and what could it not tell you? A student who reports findings without explaining method choices is demonstrating what they did, not what they understand.

Treat sources as evidence, not decoration. Dropping a long quotation into a paragraph and moving on is not analysis. Paraphrase, explain what the source reveals, and connect it explicitly to your research question. Background context follows the same rule: include it only where it directly supports your answer.

Self-check list for your draft (written for this guide, not taken from IB materials)

• Have I defined each key term my discipline uses, once, and applied it consistently throughout?
• Can I explain, in my own words, why I chose my research method and what its limitations are?
• Does every paragraph connect back to my research question, or is some of it general background?
• Am I interpreting sources and explaining their significance, or just quoting them?
• Is my background context doing work, or is it there because it seemed relevant at the time?

If any answer is "not sure", that section is where extended essay criterion b marks are most at risk.

5. Common Ways Drafts Fall Short on This Criterion

Most shortfalls under extended essay criterion B fall into a small set of patterns. Recognising them in your own draft is the fastest route to a stronger submission.

Background information that never connects to the research question. Context belongs in the essay only when it directly helps answer the question. A lengthy historical overview or detailed description of a biological system becomes dead weight if the student never refers back to it when interpreting findings. The 2027 criteria reward relevant knowledge, not volume of it.

Technical terms used inconsistently or incorrectly. Picking up vocabulary from sources without fully understanding it is a persistent problem. A term defined one way in the introduction and used differently three pages later signals to an examiner that the student is borrowing language rather than working with concepts. The principle is simple: define once, then use confidently throughout.

Sources treated as decoration. Long quotations dropped into paragraphs without explanation or connection to the argument do not count as demonstrated understanding. An examiner reads the student's own words as evidence of knowledge. Quotations that sit uninterpreted tell the reader nothing about what the student actually grasped.

A 'what I did' account of methodology instead of 'what this method allowed me to find out'. Listing procedural steps shows familiarity with a technique, not understanding of it. The distinction matters: understanding a method means knowing what it can and cannot tell you, not just describing its stages, and the case for why it suits your question is judged under Criterion A.

For interdisciplinary essays: one subject lens left underdeveloped. A student who engages rigorously with one DP subject but only gestures at the second will leave an obvious gap under Criterion B. Both lenses need to be developed with the same depth of subject-specific terminology and conceptual grounding.

6. How Criterion B Connects to the Other Four Extended Essay Criteria

Four of the five criteria are applied to the essay itself, read as a whole, and Criterion E to your reflective statement. Treating them as separate targets to chase in sequence is a practical mistake.

Criterion A (Framework for the essay, 6 marks) is where your knowledge gets organised. Per Hachette Learning, structure is explicitly assessed under Criterion A, and the new IB guide recommends a three-part structure of introduction, body and conclusion. The counter-intuitive point: an examiner can see that a student holds strong subject knowledge but still award limited marks under Criterion A if poor structure buries it. Knowledge that cannot be followed is knowledge that cannot be credited.

Criterion C (Analysis and line of argument, 6 marks) treats what you demonstrated under Criterion B as its raw material. Criterion B asks whether you know the subject matter; Criterion C asks whether you have applied that knowledge to analyse findings and build a coherent argument. One without the other collapses. A line of argument built on shaky subject knowledge will not hold, and deep knowledge that is never used analytically does not satisfy Criterion C.

Criterion D (Discussion and evaluation, 8 marks) is the most heavily weighted criterion in the 2027 model. Evaluating the significance of your findings and the effectiveness of your investigation demands the same command of subject knowledge that Criterion B rewards. The two reinforce each other directly: a student who genuinely understands the discipline can say something meaningful about why their findings matter and where the methodology was limited.

Criterion E (Reflection, 4 marks) is easy to conflate with knowledge. As the Hachette Learning guide notes, metacognition involves two distinct components: metacognitive knowledge (how you learn) and metacognitive regulation (evaluating outcomes and strategies). Criterion E asks how you grew as a learner, not what you found out about your subject. Summarising your conclusions in your reflective statement and presenting them as reflection misses what this criterion asks for.

The practical rule: if your essay is strong on subject knowledge but weak on structure, more than one score suffers. Build for the whole, not for one criterion in isolation.

7. What to Do This Week

Open your current draft now and read it paragraph by paragraph. For every subject-specific term you use, ask yourself the self-check questions from section 4: is this term defined the first time it appears? Is it used with the same meaning every time it recurs? If you find a term that shifts meaning, or one you used without defining it, mark it and fix it before your next supervisor meeting.

One non-obvious place to check: introductions. Students often use discipline-specific vocabulary loosely in the opening paragraphs, assuming it will be pinned down later. An examiner reads the essay as a whole, so a loose definition early on weakens the demonstration of knowledge throughout.

The full mark-level descriptors for Criterion B sit in the extended essay guide on the IB Programme Resource Centre, which requires a school login to access. Ask your supervisor to share the relevant pages this week.

FAQ

What is extended essay criterion B?

Criterion B is titled 'Knowledge and Understanding' and is worth 6 of the 30 marks available in the 2027 extended essay; examiners ask whether the student demonstrates knowledge and understanding of the subject matter being used in their research.

What does 'knowledge and understanding' mean in the IB extended essay?

It means accurate use of subject-specific terminology and concepts, understanding of the research methods chosen, and - for the interdisciplinary pathway - command of both DP subject lenses being integrated.

Can the extended essay criteria be changed after I submit?

No - the five criteria (Framework, Knowledge and Understanding, Analysis and Line of Argument, Discussion and Evaluation, Reflection) are fixed by the IB and applied by the external examiner to the submitted essay.

Is extended essay criterion B the same for biology, history, and language B?

The same guiding question applies across all subjects and both pathways, though what counts as relevant terminology and appropriate research methods differs by discipline; language A and language B essays no longer have sub-categories.

When is the first assessment for the new extended essay criteria?

The new five-criterion, 30-mark model applies from May 2027; November 2026 is the last session assessed on the previous model.

What are the grade boundaries for the new 30-mark extended essay?

No grade boundaries have been set yet; the IB will establish them after the May 2027 session, with results due 6 July 2027.

References

• DP extended essay updates - International Baccalaureate - https://www.ibo.org/university-admission/latest-curriculum-updates/dp-extended-essay-updates/
• Diploma Programme Subject Brief: Extended essay, first assessment 2027 (International Baccalaureate Organization, 2024) - https://www.ibo.org/globalassets/new-structure/university-admission/pdfs/ee_subjectbrief_en.pdf
• The IB Extended Essay: Structuring an Extended Essay - Hachette Learning (Joseph Koszary, 2025) - https://www.hachettelearning.com/blog/the-ib-extended-essay-structuring-an-extended-essay
• The IB Extended Essay: Extended Essay Tips - Hachette Learning (Joseph Koszary, 2025) - https://www.hachettelearning.com/blog/the-ib-extended-essay-extended-essay-tips