IB MYP Command Terms: What Explain, Evaluate, and Discuss Really Mean

Have you ever studied a topic thoroughly, felt confident about your knowledge, and still lost marks because your answer wasn't quite what the examiner expected?

Sometimes, the problem isn't what you know. It's how you respond to the question.

In the IB Middle Years Programme (MYP), command terms tell you what you are expected to do with your knowledge. A question asking you to explain requires a different response from one asking you to evaluate or discuss. If you treat all three as instructions to write everything you know, you may miss the point of the question.

Understanding these differences can help you write more focused answers, demonstrate deeper understanding, and prepare more effectively for IB MYP assessments.

Whether you're a student working towards your next assessment or a teacher helping students improve their exam technique, let's explore what these three command terms really mean, using examples from Mathematics, Physics, Chemistry, Biology, and Economics.

1. What Are IB MYP Command Terms?

Command terms are instruction words used in IB assessment questions. They indicate the type of response or thinking required.

Consider these three questions about energy:

• Explain: Explain how a solar panel generates electricity.
• Evaluate: Evaluate the effectiveness of solar energy as a source of electricity.
• Discuss: Discuss the use of solar energy as an alternative to fossil fuels.

Although all three questions relate to solar energy, each requires a different approach.

The first asks you to explain a process. The second requires you to judge effectiveness using relevant evidence and reasoning. The third invites you to explore different arguments or perspectives about using solar energy.

The topic may be familiar, but your answer must match the instruction.

The key is to understand not only what the question is about, but also what you are being asked to do with that information.

2. What Does “Explain” Mean in an IB MYP Question?

When a question asks you to explain, you need to make something clear by giving reasons, describing how a process works, or showing a connection between cause and effect.

Simply naming a fact or stating what happens is often not enough. You need to show that you understand why or how it happens.

Example 1: Biology

Question: Explain why plants need sunlight for photosynthesis.

A weak answer might be:

“Plants need sunlight because it helps them grow.”

This statement is related to the topic, but it does not explain the process.

A stronger answer would be:

“Chlorophyll absorbs light energy, which is used during photosynthesis to help convert carbon dioxide and water into glucose. The glucose can then be used by the plant for respiration and growth, or converted into other substances.”

This answer explains the role of light energy and connects it to the process of photosynthesis.

Example 2: Physics

Question: Explain why the current increases when the voltage across a fixed resistor increases.

A strong answer would explain that, provided the resistor's temperature and resistance remain constant, increasing the voltage increases the current according to Ohm's law, I = V ÷ R.

The answer does more than state that voltage and current increase together. It explains the relationship between them.

Example 3: Mathematics

Question: Explain why the equation y = 3x + 2 represents a straight line.

A suitable answer would explain that the equation is linear because the variable x has a power of 1 and the coefficient of x is constant. For every unit increase in x, y increases by 3, giving a constant rate of change and a straight-line graph.

Simply writing “because it is a linear equation” may not demonstrate enough understanding.

How to structure an “Explain” answer

Use this simple approach:

1. State the main idea.
2. Give the reason or describe the process.
3. Show how the reason connects to the outcome.

Useful sentence starters include:

• This happens because…
• The reason for this is…
• As a result…
• This leads to…
• This means that…

You do not need to use these phrases mechanically. The aim is to make your reasoning clear.

Remember: Explain means making the connection clear, not merely stating a fact.

3. What Does “Evaluate” Mean in an IB MYP Question?

To evaluate means to judge the value, effectiveness, success, or importance of something using relevant evidence and reasoning.

This is where students sometimes lose marks. They identify advantages and disadvantages but forget to make an overall judgment.

An evaluation should go beyond listing points. You need to consider how significant those points are and use them to support a conclusion.

Example 1: Economics

Question: Evaluate the effectiveness of a government subsidy in increasing the consumption of a good.

A limited answer might say:

“A subsidy reduces production costs and can lower prices. However, it costs the government money.”

Both points are relevant, but the answer does not clearly evaluate the policy's effectiveness.

A stronger answer would be:

“A government subsidy can encourage producers to supply more of a good by reducing their production costs. If the lower costs lead to lower prices, consumers may purchase more. However, the effectiveness of the subsidy depends on factors such as how much costs fall, how producers respond, and how sensitive consumers are to price changes. Overall, the subsidy may increase consumption, but its success depends on how strongly it affects prices and consumer demand, as well as its cost to the government.”

This response considers benefits and limitations before reaching a qualified judgment.

Example 2: Chemistry

Question: Evaluate the suitability of a particular material for a given purpose.

Imagine you are evaluating whether aluminium is suitable for making a drinks can.

You might consider its low density, resistance to corrosion, ability to be shaped, cost, and recyclability. You would then weigh these properties against the requirements of the product and make a judgment about its suitability.

Simply listing aluminium's properties is not enough. You must explain how those properties affect its suitability for the intended use.

Example 3: Mathematics

Question: Evaluate whether a student's solution to a problem is reasonable.

You would check the method, calculations, assumptions, and final result. If the answer is mathematically correct but unrealistic in the context of the problem, you should explain why.

For example, if a calculation gives a negative number of people, you would need to recognise that the result is not meaningful in that context and consider whether the model or interpretation needs to be checked.

How to structure an “Evaluate” answer

Try this approach:

1. Identify the strengths, benefits, or positive aspects.
2. Consider limitations, weaknesses, or alternative explanations.
3. Use evidence, calculations, examples, or relevant reasoning.
4. Reach an overall judgment that follows from your analysis.

Useful sentence starters include:

• One advantage of this approach is…
• However, a limitation is…
• This is effective because…
• The evidence suggests that…
• Overall, this approach is effective to a large extent because…

Your conclusion does not have to be entirely positive or negative. A balanced judgment is often more convincing when it reflects the evidence.

Remember: Evaluate means weighing the evidence and making a reasoned judgment.

4. What Does “Discuss” Mean in an IB MYP Question?

To discuss means to present a reasoned account that explores different arguments, perspectives, or aspects of an issue.

Depending on the subject and question, this may involve comparing viewpoints, examining advantages and disadvantages, or considering different explanations.

A discussion is not simply a list of opinions. Each point should be relevant and developed with reasoning or evidence.

Example 1: Economics

Question: Discuss the advantages and disadvantages of indirect taxes on goods such as cigarettes.

A weak answer might say:

“Indirect taxes increase prices and reduce consumption. However, people may still buy cigarettes.”

These points are relevant, but they need further development.

A stronger answer would be:

“An indirect tax on cigarettes increases the cost of supplying them, which may lead to higher prices for consumers and reduce consumption. Lower consumption could improve public health and reduce some of the wider costs associated with smoking. However, the extent of the reduction depends on how responsive consumers are to price changes. If demand is relatively inelastic, consumption may fall only slightly, while lower-income consumers who continue smoking may face a greater financial burden. Therefore, the effects of the tax depend on consumer behaviour and the wider policy objectives.”

This response explores different effects and explains why the outcome may vary.

Example 2: Physics

Question: Discuss the use of renewable energy sources to generate electricity.

A developed answer might consider the benefits of renewable energy, such as reduced dependence on fossil fuels and lower direct greenhouse gas emissions during electricity generation. It could also explore limitations, including the variable output of some sources, the need for energy storage, and the availability of suitable locations.

The aim is to examine the different considerations rather than simply declare renewable energy good or bad.

Example 3: Biology

Question: Discuss the benefits and limitations of using biological control to manage agricultural pests.

You might explore how biological control can reduce the need for chemical pesticides and may help manage pest populations over time. You could also consider the possibility that introduced control organisms affect non-target species or that pest control may not be immediate.

A strong response develops the relevant points and explains why the method may be suitable in some situations but less effective in others.

How to structure a “Discuss” answer

Use this approach:

1. Introduce the issue or main idea.
2. Develop one relevant argument or perspective.
3. Explore another argument, perspective, or important consideration.
4. Explain the significance of the points you have discussed.
5. Provide a conclusion when appropriate.

Useful sentence starters include:

• One important consideration is…
• On the other hand…
• Another perspective is…
• This suggests that…
• Taken together, these points indicate that…

Not every discussion question requires an identical structure. Let the wording of the question guide your response.

Remember: Discuss means exploring relevant arguments or perspectives in a reasoned way.

5. Explain vs Evaluate vs Discuss: What Is the Difference?

The easiest way to understand these command terms is to compare what each one expects you to do.

Explain

Explain means showing how or why something happens. You should describe the process, give reasons, and connect causes to their effects.

For example, in Biology, if a question asks you to explain photosynthesis, you should describe how plants use light energy, carbon dioxide, and water to produce glucose and oxygen.

Ask yourself: What causes this? How does it work?

Evaluate

Evaluate means judging how effective, useful, or successful something is. You should consider evidence, strengths, and limitations before reaching a reasoned conclusion.

For example, in Economics, if you are asked to evaluate a government subsidy, you should consider its benefits, such as making essential goods more affordable, as well as its limitations, such as the cost to the government.

Ask yourself: How well does it work? What evidence supports my judgment?

Discuss

Discuss means exploring different arguments, perspectives, or aspects of an issue. You should develop your points with relevant reasoning and examples, considering different sides before reaching a conclusion where appropriate.

For example, in Physics, if you are asked to discuss the use of renewable energy, you could consider its environmental benefits alongside challenges such as storage, cost, and the availability of suitable locations.

Ask yourself: What are the different considerations, and why do they matter?

Let's use one topic to see the difference.

Imagine you are studying solar energy.

• Explain: Explain how a solar panel generates electricity. Describe the process and how light energy is converted into electrical energy.
• Evaluate: Evaluate the effectiveness of solar energy in meeting a city's electricity needs. Consider its benefits, limitations, and the evidence before making a judgment.
• Discuss: Discuss the use of solar energy as an alternative to fossil fuels. Explore relevant benefits, limitations, and wider considerations.

The topic stays the same, but the type of thinking changes.

6. How to Answer Command-Term Questions Without Losing Focus

Knowing the definitions is useful, but you also need to apply them when answering assessment questions. Before you begin writing, take a moment to plan.

Step 1: Find the command term

Read the question carefully and identify the instruction word. Avoid rushing straight into writing everything you remember about the topic.

Step 2: Identify the exact focus

Ask yourself what the question is specifically asking about.

If it asks you to evaluate the effectiveness of a government subsidy, for example, your answer should focus on how effective the subsidy is, not simply define a subsidy.

Step 3: Decide what your answer needs

For explain, identify the process, reasons, or relationships you need to describe.

For evaluate, identify the evidence, strengths, limitations, and judgment you can support.

For discuss, identify the relevant arguments, perspectives, or aspects that need to be explored.

Step 4: Support your points

Use subject-specific evidence and reasoning. Depending on the subject, this might include calculations, scientific principles, experimental data, economic diagrams, examples, or relevant terminology.

Step 5: Check your response

Before moving on, ask yourself:

• Have I answered the actual question?
• Have I followed the command term?
• Have I supported my points with relevant reasoning or evidence?
• Have I included a judgment or conclusion where the question requires one?

A response may contain accurate information but still be incomplete if it does not fulfil the instruction.

7. Practice: Can You Identify What Each Question Requires?

Try these three questions. Before answering, identify what the command term requires you to do.

Question 1 — Chemistry

Explain why increasing the temperature generally increases the rate of a chemical reaction.

Question 2 — Economics

Evaluate the effectiveness of a maximum price set below the equilibrium price in making a good more affordable.

Question 3 — Biology

Discuss the benefits and limitations of using biological control to manage agricultural pests.

Now consider what a successful answer would need to include.

• Question 1: Explain how increasing temperature affects particle kinetic energy, collision frequency, and the proportion of collisions with enough energy to react.
• Question 2: Consider how a maximum price may improve affordability for some consumers, while also examining possible shortages and other consequences. Reach a judgment based on the circumstances.
• Question 3: Explore relevant benefits and limitations of biological control, supporting your points with biological reasoning and suitable examples.

Notice that each question calls for a different approach. The first focuses on a scientific explanation, the second requires a judgment about an economic policy, and the third explores multiple considerations.

For additional practice, take a topic you are currently studying and write one question using each command term. Answer them separately and compare how your responses differ.

8. How Teachers and Tutors Can Help Students Master Command Terms

Students often encounter command terms across different subjects, but they may not immediately recognise what each one requires in practice.

Teachers and tutors can help by making the expected thinking explicit.

Model the differences. Use questions on the same topic that begin with explain, evaluate, and discuss. Show students how the purpose and structure of each answer change.

Compare different-quality answers. Ask students to identify what is missing when an answer lists facts without explaining them, makes a judgment without evidence, or presents only one side of a discussion.

Give specific feedback. Instead of simply writing “add more detail,” explain whether the student needs to develop a cause-and-effect link, support a judgment, or explore another relevant perspective.

Use short, targeted practice. Regular practice with Mathematics, Physics, Chemistry, Biology, and Economics questions can help students apply command terms before longer assessments.

Encourage self-assessment. Ask students to identify the command term before answering and check afterwards whether their response fulfils the instruction.

These strategies can help students become more independent learners and make revision sessions more purposeful.

9. Make Command Terms Part of Your Revision Routine

You do not need to memorise long definitions or use a complicated answer template for every question. Instead, build the habit of pausing briefly before you respond.

When you see explain, make the reasoning clear.

When you see evaluate, weigh the evidence and reach a supported judgment.

When you see discuss, explore the relevant arguments or considerations in a reasoned way.

Remember that command terms are only one part of an assessment. Read the full question, pay attention to the subject context and available marks, and follow the relevant assessment criteria and teacher instructions. The depth and length of your answer should suit the task.

RevisionPrep offers IB MYP and Diploma Programme question banks and revision resources for Mathematics, Physics, Chemistry, Biology, and Economics. Practicing questions from these subjects, checking your answers against available mark schemes, and reviewing mistakes can help you become more confident in applying your knowledge to assessment-style questions.

The next time you face an IB MYP question, do not begin writing immediately. Identify the command term, plan what your response needs to demonstrate, and answer the question that was actually asked.

That small habit can make a meaningful difference to the clarity and quality of your work.

RevisionPrep is an independent IBDP & MYP question bank built by experienced educators — for students, tutors, and schools. It is not affiliated with, endorsed by, or connected to the International Baccalaureate Organization (IBO).

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