IB Physics command terms 2026: What they mean and how to respond correctly

IB Physics command terms are the action words in exam questions that tell students exactly what type and depth of response is required. Terms such as state, describe, explain, calculate, determine, analyse, and evaluate each carry different expectations in the markscheme. They also influence how much working, reasoning, and detail students should include for a given mark allocation.

Learning to respond precisely to these terms helps students avoid over-writing simple answers, missing key reasoning steps, and losing marks in Paper 2.

Why understanding command terms is essential for scoring high in IB Physics

The International Baccalaureate Organisation publishes its command terms as part of the official IB Physics ^[1] subject guide. These are not suggestions. They are precise instructions that signal how deeply you must engage with a question. Misreading a command term is not a knowledge failure; it is a strategy failure.

A common mistake we see at Times Edu is a student who writes a beautiful, detailed explanation in response to a “state” question, spending three minutes on a one-mark answer while running out of time for a six-mark “evaluate” question at the end of the paper. The reverse is equally damaging: A student who lists a single fact in response to an “explain” question, leaving the cause-and-effect chain completely empty, scores one mark out of four.

The IBO groups command terms by the cognitive level they target, from basic recall to high-order critical analysis. Knowing which group a command term belongs to immediately tells you how long to write, how much physics reasoning to include, and whether calculations are required.

>>> Read more: IB Physics books 2026: Complete guide for students and teachers

State and identify in IB Physics: How much detail is expected

The command terms “state” and “identify” both sit at the lowest cognitive level, often called Objective 1. They require brief, direct answers with no explanation attached.

State asks you to give a specific name, value, or piece of information without justification. For example: “State the principle of conservation of momentum.” A correct answer is one precise sentence: The total momentum of a closed system remains constant, provided no external net force acts on it. You do not explain why. You do not give an example. You stop there.

Identify asks you to select or name something from a given context. For instance: “Identify the type of wave shown in the diagram.” The answer is either transverse or longitudinal, supported by one observation from the diagram if the question demands it.

One critical detail often overlooked is the word “list.” List questions are essentially a series of “state” answers placed one after another. No elaboration, no linking sentences. Students who write paragraphs in response to “list” questions waste precious time without gaining a single extra mark.

>>> Read more: IB Physics HL Mixed Practice Sets 2026: The Smart Way to Master Exam-Style Questions

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Describe and explain in IB Physics: The key differences and how to answer each

This is the pairing that causes the most confusion, and the most mark loss, across all IB Physics papers. The gap between “describe” and “explain” is not subtle; it is structural.

Describe asks you to give an account of what happens. You are reporting observable facts, patterns, or sequences without being required to state the underlying cause. For example: “Describe how the current in a filament lamp changes as the potential difference across it increases.” A correct response explains that the current increases but at a decreasing rate, producing a non-linear I-V characteristic. No mention of lattice vibrations is required at this stage.

Explain changes everything. When you see “explain,” you must provide the cause-and-effect chain behind the phenomenon. Using the same filament lamp scenario: “Explain why the resistance of a filament lamp increases with temperature.” Now you must state that as current increases, the temperature of the filament rises, which causes the lattice ions to vibrate with greater amplitude, increasing the frequency of collisions with conduction electrons, and therefore increasing resistance. Each logical link must appear explicitly. The markscheme for an “explain” question will reward each link in that chain separately.

Drawing on years of experience at Times Edu, our tutors train students to use a simple test before writing their answer: Ask yourself, “Does this question require me to say what happens, or why it happens?” The answer to that question determines whether you write a describe-level or explain-level response.

The describe versus explain distinction is arguably the most important concept in the entire category of IB Physics Paper 2 command words. A student who confuses these two terms on a four-mark question typically scores no more than one mark regardless of how accurate their physics knowledge is.

>>> Read more: IB Physics HL Explain Questions : PEE Method for Long Answer Marks

Calculate and determine in IB Physics: What level of working is required

Both “calculate” and “determine” require you to arrive at a numerical answer, but they differ in how you are expected to get there.

Calculate is direct: Obtain a numerical answer by showing all relevant stages of working. This means writing the formula first, substituting values with units, and arriving at a clearly labeled final answer with the correct unit. If you skip steps, you risk losing method marks even if your final number is correct. Never simply write the answer without working.

Determine goes one level further. It asks you to obtain the only possible answer, often by combining two or more methods, including graphical analysis. For example: “Determine the half-life of the radioactive source from the graph.” You must explain how you read the graph, state the values you extracted, and then apply the relevant formula. The word “determine” signals that the path to the answer is part of what is being assessed.

A common mistake we see is students treating “determine” like a simple calculation. They skip the graphical or logical reasoning step, write the numbers, and lose the marks allocated specifically for method and analysis.

Show that is a related term worth addressing here. This command asks you to prove a given numerical result algebraically. The critical rule: Never begin your working with the value you are trying to prove. Start with base formulas, substitute step by step, and arrive at the given result as your final line. Examiners are checking that you understand the derivation, not that you can work backwards from a printed number.

Evaluate, analyse and deduce in IB Physics explained

These three command terms cluster at the highest cognitive level. They are the terms that separate students aiming for a 6 from those reaching a 7. They appear most frequently in the structured response and extended response sections of Paper 2.

Evaluate requires you to assess the merits, limitations, or implications of a method, result, or argument. A typical question might read: “Evaluate the use of a spring balance to measure gravitational field strength.” Your answer must go beyond description. You need to identify at least one strength and one weakness, support each with physics reasoning, and often conclude with a justified judgment. The markscheme for evaluate questions almost always includes a point for a balanced conclusion.

In our experience working with international students, the most common error on “evaluate” questions is writing only positive or only negative points. Balance is not optional; it is built into the marking criteria.

Analyse asks you to break down information or data into its component parts and examine how they relate. For example: “Analyse the motion of the ball based on the velocity-time graph provided.” You are expected to identify each phase of motion, state what the gradient and area represent, and draw conclusions about acceleration, displacement, or net force during each phase. Analyse responses reward structure: Address each component in a logical sequence.

Deduce requires you to draw a logical conclusion from given information. Unlike “calculate,” you are not always performing arithmetic. You might be asked to “deduce the relationship between pressure and volume from the data table,” requiring you to identify the mathematical pattern and state the law it supports. If a calculation is involved, show it. If it is purely logical, state your reasoning step by step.

One critical detail often overlooked on “deduce” questions is that students frequently state the conclusion without showing the reasoning that leads to it. The conclusion alone earns no marks. The reasoning is where the marks live.

How command terms affect mark allocation in IB Physics papers

The number of marks attached to a question is directly tied to the command term used. Understanding this relationship allows you to allocate your exam time efficiently and avoid the two most common time management failures in IB Physics: Over-answering low-mark questions and under-answering high-mark questions.

As a practical rule, each mark on the markscheme corresponds to one distinct point, fact, or reasoning step. A two-mark “describe” question expects two observable features. A four-mark “explain” question expects four linked cause-and-effect steps. A six-mark “evaluate” question expects strengths, weaknesses, and a conclusion supported by reasoning.

Drawing on years of experience at Times Edu, our consultants consistently observe that students who write to the mark allocation, rather than writing until they run out of ideas, perform significantly better under timed conditions. A six-mark “evaluate” question should receive six distinct scoring points, not a 400-word essay with repeated ideas.

The mark allocation command terms relationship in IB Physics is not incidental. It is by design. The IBO structures its papers so that objective-level questions take less time and objective-three questions take more, with the expectation that students have practiced exactly this type of strategic time allocation.

Frequently asked questions

What are the IB Physics command terms and why do they matter?

IB Physics command terms are specific action words used in exam questions to indicate the exact type and depth of response required. They matter because the markscheme is written entirely around them. An answer that ignores the command term, no matter how physically accurate, cannot score full marks.

What is the difference between describe and explain in IB Physics?

“Describe” asks you to report what happens: The observable facts, patterns, or sequence of events. “Explain” asks you to go further and state why it happens, using a chain of physics principles to link cause and effect. Marks are allocated to each link in an explain answer, so every reasoning step must appear explicitly.

What does determine mean in IB Physics and how should you structure your answer?

“Determine” means you must obtain the only possible answer, typically by combining calculation with analysis, often from a graph or data set. Your response should state how you extracted data, show all calculation steps with units, and clearly state the final answer with appropriate significant figures.

What does evaluate mean in IB Physics exam questions?

“Evaluate” requires you to assess a situation, method, or result by identifying its strengths and limitations and supporting each with physics reasoning. A strong evaluate answer is balanced, provides evidence for each point, and ends with a justified conclusion. One-sided responses consistently lose the concluding mark.

What is the difference between state and outline in IB Physics?

“State” requires a single direct fact, value, or name with no elaboration. “Outline” sits one level higher and asks for a brief summary that includes the essential features of a concept, process, or phenomenon. An outline is broader than a state answer but does not require the depth of an explain response.

How do command terms affect how much you need to write in IB Physics?

Command terms, combined with the mark allocation, directly determine how much you should write. Low-level terms like “state” and “list” require one sentence or less per mark. High-level terms like “evaluate” and “analyse” require structured, multi-sentence responses that address each scoring point individually. Writing more than necessary for low-level questions wastes time without adding marks.

Which IB Physics command terms appear most frequently in Paper 2?

Based on past IB Physics Paper 2 papers, the command terms “explain,” “calculate,” “describe,” “determine,” and “sketch” appear with the highest frequency. “Evaluate” and “analyse” appear in extended response questions, particularly in the longer structured questions in Section B. Mastering these five core terms and the two higher-order terms covers the vast majority of the paper.

Conclusion

At Times Edu, our 1-on-1 IB Physics tutoring programme is built around exactly this kind of exam-ready thinking. We do not just teach physics content; we train students to read questions the way examiners write them. If your student is preparing for IB Physics Paper 2 and wants a structured, personalised academic roadmap that addresses command term strategy alongside content mastery, our consultants are ready to help. Book a personalised consultation with Times Edu today and give your student the strategic edge that separates a good score from a great one.

Charlotte