IB Academic Vocabulary Guide | How to Build Subject-Specific English Vocabulary Across All IB Subjects

Why Does Vocabulary Actually Matter in the IB—and What Should You Do First?

The honest answer: vocabulary is not the whole game, but it is the foundation of every essay, every internal assessment, and every paper you write. Students who consistently score well across multiple subjects are not necessarily the most creative thinkers in the room—they are often the ones who can express precise ideas in precise language, without fumbling for words mid-argument.

The most efficient first move is to stop studying vocabulary in isolation and start collecting it from the texts you are already reading.

Flashcard apps with decontextualized word lists have their place, but IB-level academic vocabulary is dense, discipline-specific, and deeply tied to how ideas are structured in each subject. A word like "equilibrium" means something different in Economics, Chemistry, and Biology—and the essay conventions around it differ too. Treating vocabulary as a separate subject to memorize before applying it is the long way around. The short way is to build a living vocabulary system inside your normal study routine.

This guide walks through exactly how to do that, subject by subject, across the full Diploma.

How Is IB Academic Vocabulary Different From General English Vocabulary?

IB academic vocabulary sits at the intersection of three layers, and understanding the distinction saves you a lot of wasted effort.

Most vocabulary guides focus only on the first layer. IB students need all three—and in a specific order.

Start with IB command terms before anything else

IB examiners use a controlled vocabulary of command terms—words like evaluate, discuss, examine, and compare and contrast—that carry very specific meanings in the marking context. Misreading a command term is one of the fastest ways to lose marks, not because you lack knowledge, but because you answered a different question than the one asked.

Always check the latest official subject guide for your exact syllabus version. Command terms can shift between curriculum cycles, so confirm with your teacher or IB coordinator which version applies to you.

What Is the Most Efficient System for Building Vocabulary From Your Own Study Material?

The cycle that works across subjects is: Collect → Define in context → Reuse in writing → Review.

Step 1: Collect in sentences, not just words

When you encounter an unfamiliar word or useful phrase while reading a textbook, past paper, or source text, do not just note the word. Note the sentence. The sentence carries the grammatical pattern (what comes before and after the word), the register (formal vs. informal), and the meaning in context.

Example from an Economics text:

"The policy resulted in a significant deadweight loss, reducing overall allocative efficiency within the market."

You now have: deadweight loss, allocative efficiency, and the connecting phrase "resulting in… reducing overall…" all in one capture.

Step 2: Define in your own words, in the same subject

Write a short definition of the term as it applies to that subject—not a dictionary definition copied from somewhere else. This forces active processing. If you cannot write the definition yourself yet, you haven't understood the term enough to use it in an essay.

Step 3: Reuse within 48 hours

The strongest predictor of vocabulary retention is production under pressure. Write a practice paragraph—even two or three sentences—using the new term correctly. Tying it to a past-paper question makes this doubly useful, because you are also practising your exam technique at the same time.

For more on how to use past papers productively at every stage of revision, see our guide on IB最終試験 直前対策｜過去問とmarkschemeの使い方.

Step 4: Review with spaced repetition

After the initial 48-hour reuse, schedule review at gradually increasing intervals. Apps like Anki work well here—but only if your flashcard contains the full sentence, not just the isolated word.

How Should You Build a Subject-Specific Phrase Bank? (History, Economics, Biology, and More)

A phrase bank is different from a vocabulary list. It is a collection of ready-to-use academic sentence frames and evaluative phrases that are natural and appropriate for a specific subject. Think of it as your pre-loaded toolkit for constructing arguments under exam time pressure.

History

Historiographical writing demands language for presenting, attributing, and challenging scholarly interpretations. High-value phrase categories include:

• Attributing arguments to historians: "According to [historian], the primary cause was…" / "[Historian]'s interpretation emphasizes the role of…"
• Introducing counter-arguments: "However, this view has been contested by…" / "A revisionist perspective would argue that…"
• Evaluating significance: "This event proved pivotal in that it…" / "The long-term consequences of this policy can be traced to…"
• Hedging claims appropriately: "It could be argued that…" / "The available evidence suggests, though does not conclusively prove, that…"

Economics

Economics essays, particularly extended response questions, require the language of cause-and-effect, policy analysis, and evaluation. Build phrases for:

• Describing economic mechanisms: "An increase in X leads to a shift in… resulting in…"
• Evaluating policies: "In the short run… however, in the long run…" / "The effectiveness of this policy depends on the price elasticity of…"
• Integrating diagrams into prose: "As illustrated in the diagram above, the equilibrium price falls from P1 to P2 as a result of…"

For a deeper look at how evaluation language translates to marks in extended response questions, see IB経済 HL 完全ガイド｜評価・15マーク問題・IAの書き方.

Biology and Chemistry

The sciences require precise, passive-voice-heavy language for describing processes and findings, alongside evaluative language for discussion sections of Internal Assessments.

• Describing methodology and results: "The rate of reaction was found to increase proportionally with…" / "The data suggest a positive correlation between…"
• Evaluating experimental design: "A significant limitation of this investigation was…" / "To improve the reliability of the results, future investigations could…"
• Drawing biological/chemical conclusions: "This supports the hypothesis that…" / "The anomalous result for Trial 3 may be attributed to…"

For subject-specific vocabulary and conceptual language used in each discipline, see the full subject guides: IB生物 HL 完全ガイド｜暗記に頼らない勉強法と点の取り方 and IB化学 HL 完全ガイド｜難易度・勉強法・点の取り方.

TOK and EE

Theory of Knowledge and the Extended Essay share a common need for philosophical hedging language and meta-analytical phrases—language that steps back from a claim and reflects on its nature.

• "This raises the question of whether…"
• "The distinction between X and Y is significant here because…"
• "One might object to this claim on the grounds that…"
• "The extent to which this conclusion holds depends on how we define…"

How Do You Use Source Texts and Past Papers as Vocabulary Input?

Past papers and the texts used in assessments are the highest-quality vocabulary sources available to IB students—and they are free. They are written at exactly the register you need to produce, in exactly the subjects you are studying.

Mining past papers for language

When you work through a past paper, do not discard the mark scheme immediately after checking your answers. Read the examiner's markscheme closely. Pay attention to:

• The specific terms used to describe what a "good answer" includes
• The evaluative language the markscheme itself uses ("the response demonstrates nuanced understanding of…")
• The phrasing used in model answer extracts, where available

These phrases are not just model answers—they are a direct signal of the register and precision the examiner is expecting.

Using English A source texts as vocabulary input

For students in IB English A (Language and Literature), the unseen texts in the exam are, by definition, unfamiliar. But the language of literary analysis can be collected and practised systematically:

• Analytical connectives: "The juxtaposition of X and Y creates a sense of…" / "Through the use of [technique], the author foregrounds…"
• Structural observations: "The shift in register in the third stanza signals…" / "The opening paragraph establishes the central tension between…"

Sciences: using journal-style language in IA writing

If you are writing an Internal Assessment in Biology, Chemistry, or Physics, reading a few age-appropriate scientific abstracts and discussion sections (even simplified ones from sources aimed at undergraduate students) is one of the fastest ways to internalize the passive, hedged, evidence-referencing language that science IA rubrics reward. For a practical breakdown of what high-scoring IAs look like structurally, see IB Internal Assessment (IA) の書き方｜高得点を取る型と進め方.

What Are the Most Common Vocabulary Mistakes IB Students Make in Essays?

Understanding what goes wrong helps you avoid it deliberately. These patterns appear across multiple subjects and assessment types.

1. Overusing "thesaurus vocabulary"

Replacing a simple, accurate word with a longer, rarer one—for the sake of sounding academic—usually backfires. If the more complex word is not exactly right, examiners notice the mismatch. Precision matters more than impressiveness.

2. Using subject-specific terms without defining them

In many IB subjects, you are expected to demonstrate understanding of terminology by using it accurately in context, rather than simply naming it. Dropping a term like comparative advantage or allelic frequency into a sentence without showing you understand what it means loses marks, even if the term itself is correct.

Good habit: When you introduce a key term for the first time in an essay, either define it briefly in the same sentence or use it in a way that demonstrates its meaning implicitly.

3. Mixing registers across a single piece of writing

Academic writing requires consistency. Casual language ("This basically shows that…", "a lot of people think…") jarring against formal analysis weakens the overall impression. If you have built subject-specific phrase banks, this is largely self-correcting—you reach for formal structures automatically.

4. Evaluative vocabulary without evaluative reasoning

IB rubrics—across History, Economics, English, and others—explicitly reward evaluation. But many students learn evaluative phrases ("however," "on the other hand," "this is limited because…") without attaching them to real reasoning. The phrase is the signal; the reasoning is the content. Both are required.

How Do You Maintain Vocabulary Growth Across Two Years Without Burning Out?

Vocabulary building does not need to be a separate daily task. The most sustainable approach folds it into work you are already doing.

Weekly minimum habits (low-effort, high-return):

• When finishing a set of practice questions or a reading task, spend five minutes noting two or three phrases worth reusing. This takes less time than it sounds if you do it immediately rather than planning to do it later.
• Before submitting any piece of writing (essay, IA draft, TOK paragraph), scan it for places where you repeated the same word or phrase more than twice in a short span. Replace at least one instance with a more precise alternative from your phrase bank.
• When returning a marked essay, read teacher comments for vocabulary-level feedback. Teachers often signal register problems in phrasing ("clarify this term," "be more precise here") that are worth turning into vocabulary notes.

Semester-level habits:

• Before each exam season, review your phrase bank for each subject and reduce it to a shortlist of ten to fifteen structures you want to actively use. Trying to use everything at once is counterproductive.
• If you are working on your Extended Essay, pay particular attention to the academic vocabulary conventions of the discipline you have chosen. EE marker reports frequently note that students underestimate how much the register of a History EE differs from a Biology EE.

Quick Reference: High-Value Vocabulary Categories by Subject

Vocabulary in the IB is not a separate subject—it is the medium through which your knowledge becomes visible to an examiner. Build it from your real study material, organise it by subject, and deploy it deliberately in every draft you write.

If you would like guidance on how vocabulary and argumentation work together in specific subjects or assessment types, the teachers at Quick IB—all IB graduates themselves—can work through your actual writing with you and give feedback grounded in real examiner expectations.