How to Answer

This lesson covers what to do in the room. Whatever the question, almost every good answer has the same shape: make sure you understand the question, give it a structure, reason through it out loud, and use whatever the tutor adds. We'll go through each of these, then follow one real question from start to finish.

In an exam you work out the answer, then write it down. In the interview, the working is the answer. Tutors can only assess reasoning they can hear, and they can only help you if they know where your thinking has got to. A minute of silence followed by a correct answer tells them almost nothing.

Thinking out loud doesn't mean talking non-stop or being polished. It means saying the decisions as you make them: what you know, what you're unsure of, what you're trying next and why. A pause you have asked for ("Can I have a moment to think about that?") is fine. An unexplained silence isn't. Half-formed ideas are fine too, and a wrong idea with a reason is useful, because it gives the tutor something to respond to.

Three habits make your thinking much easier to follow:

• Be precise. Use numbers, units and the right terms. Vague words such as "affects" make it sound as if you don't know the mechanism, even when you do.
• Use your paper. Sketch diagrams, graphs and working as you talk, and in an online interview hold them up to the camera.
• Stop when you've answered. Tutors interrupt to steer, not to criticise. Let them, and don't fill the time by going back over material nobody asked for.

The first twenty seconds of an answer decide how the rest of it goes. Whatever the question, start the same way.

1. 1.Check you understand the question. Say it back in your own words: "So you're asking why glucose ends up in the urine, rather than how it gets into the blood?" The most common way to lose marks without noticing is to answer a slightly different question from the one you were asked, such as explaining how the kidney works when you were asked why glucose appears in urine. Restating catches this at once, and the tutor will correct you if you've misread it.
2. 2.Clarify anything you don't know. If there is a word, a fact or a piece of the scenario you don't understand, ask. "I haven't come across that term. Could you tell me what it means?" "Is this patient otherwise healthy?" "Do you mean over a few minutes or over years?" Tutors expect this, and a precise clarifying question shows you are thinking carefully, which is exactly what a doctor does when taking a history. What doesn't work is asking a question to fish for the answer ("Is it something to do with the kidney?"). Clarify the question, then answer it yourself.
3. 3.Give an overview of your answer. Before going into detail, say in a sentence or two how you are going to approach it. "I think there are two parts to this: why blood glucose is high in diabetes, and why that high level ends up in the urine. Let me take the first one first."

The overview is the step most applicants skip, and it does more than any other. It gives you a structure to come back to when you lose your place under pressure. It lets the tutor follow you, and redirect you within ten seconds if you are heading the wrong way, rather than after three minutes. It shows organised thinking, which is one of the things tutors are assessing. And it buys you thinking time without any silence.

What the overview looks like depends on how much you know:

• If you know the answer, list the parts: "There are three stages: how the signal arrives, how it crosses the gap, and how it is switched off."
• If you don't, give your plan: "I'm not sure yet, but I'd start with what normally happens to glucose in the kidney, then see what changes in diabetes."
• If you have a hunch, state it as something to test: "My first thought is that the kidney can only handle so much glucose. Let me check whether that holds."

Keep it short: for a simple question, one line is enough. And you can change it as you go. If a third part turns up halfway through, just say so.

Most interview questions aren't asking what you remember. They are asking you to reason from what you know to something you haven't been taught. The most common mistake is to search your memory for the answer, find nothing, and stall. Instead, build the answer step by step.

1. 1.Start from what you know. Say which part of your A-level science is relevant, even if it seems basic. The principles in Lesson 3 are a good place to look. Does something have to be conserved? Is there a gradient? Could something become saturated?
2. 2.Suggest an answer, with a reason. "I think it could be X, because Y." Don't wait until you are sure. The reason is what the tutor is assessing.
3. 3.Trace any change through. For any "what would happen if...?" question, go in three steps: what normally happens, what has changed, and what follows from that. Say which direction the change goes, and why.
4. 4.Test it yourself. Check your idea against everything you have been told, and look for the obvious objection before the tutor does: "One problem with that is..." Finding the flaw in your own idea is one of the strongest things you can do in an interview.
5. 5.Conclude. Finish with your answer in one sentence, then stop.

When a follow-up seems to come straight out of what you just said, such as "What does that assume?" or "So what would you expect?", the answer is usually already in your previous answer. Go back to it rather than starting again.

This is one of Oxford's published sample questions. The tutor's side follows the explanation Oxford gives of how the question is meant to unfold.

Tutor: Why is sugar in your urine a good indicator that you might have diabetes?

A weaker answer: "Because diabetics have high blood sugar, so some of it comes out in the urine."

A stronger answer: "So the question is why finding glucose in urine points to diabetes. I think there are two parts: why blood glucose is high in diabetes, and why that ends up in the urine when normally none does. The first part I know: in diabetes insulin isn't doing its job, so blood glucose rises. For the second, urine is made by the kidneys filtering the blood, so more glucose in the blood should mean more in the filtrate. But healthy people have glucose in their blood too and none in their urine, so something must normally stop it getting through. I'm not sure what that is yet."

The weaker answer is true, but it stops at a fact and gives the tutor nothing to work with. The stronger one restates the question, splits it into two parts and says so before starting, so both the applicant and the tutor know where the answer is going. It answers the part it knows, then notices a problem with its own explanation and says exactly where its knowledge runs out. That gap is where the tutor wants to go next.

Tutor: Good. Glucose is small enough to pass through the filter. So in a healthy person, where does it go?

A weaker answer: "I'm not sure, we haven't covered the kidney in detail."

A stronger answer: "If it is filtered but doesn't reach the urine, it must be taken back into the blood somewhere along the tubule. Glucose can't cross a membrane on its own, so I'd expect a carrier protein in the cells lining the tubule to move it back."

Not having covered a topic is not a reason to stop. The stronger answer reasons from two things on every syllabus: the glucose has to go somewhere, and it needs a protein to cross a membrane.

Tutor: Yes, a carrier protein. Does that remind you of anything, and what might limit how well it works?

A weaker answer: "Maybe it runs out of energy?"

A stronger answer: "The carrier has to bind glucose, which is like an enzyme binding its substrate. An enzyme reaches a maximum rate when all its active sites are occupied, so I'd expect the carriers to have a maximum too. Once they are all in use, glucose can't be reabsorbed any faster."

The tutor's question contained a hint: "does that remind you of anything". The weaker answer ignores it and guesses. The stronger one takes the hint, finds the comparison with enzymes, and uses it to answer the second half of the question.

Tutor: So what happens in diabetes?

A stronger answer: "Blood glucose is high, so more glucose is filtered than the carriers can reabsorb. They are saturated, and the extra stays in the tubule and ends up in the urine. So glucose in the urine tells you that blood glucose has gone above the level the kidney can recover."

The applicant didn't know this answer at the start. They got there by setting out a plan, reasoning from A-level knowledge, and using what the tutor added. Two of the steps used principles from Lesson 3: conservation (the glucose has to go somewhere) and saturation (carriers have a maximum rate). The final answer is one clear sentence that answers the question as it was asked.

Nothing a tutor adds is incidental. A new fact, a rewording, a second graph or a "suppose that..." is there for a reason, so your next sentence should use it: "If that's true, then..." Often it rules out what you have just said. Say so plainly and adjust: "That means my first idea can't be right, so instead..." Changing your mind for a good reason counts in your favour. Defending your first answer against new evidence is one of the clearest ways to do badly.

What the tutor's prompts usually mean

Tutors rarely say "you're wrong" or "you're nearly there". They steer with prompts, and recognising them is one of the most useful skills you can have. The table below is not something to learn. It is there for context, to show the kinds of prompt tutors use, and as a reference to come back to after a mock interview.

Graphs and tables come up in most interviews, and the most common error is interpreting them before reading them properly. Whatever the graph, do the same things first, out loud, before you answer the question you were asked.

1. 1.What is on each axis, and in what units? Say it. Most misreadings happen here.
2. 2.What does each line or bar stand for? If there is more than one, name them.
3. 3.Where does it start, where does it end, and what happens in between? Give two or three numbers read off the graph.
4. 4.Then, and only then, what might explain it.

This takes half a minute and gives you time to think. It also gives the tutor an accurate description to build on, which most of the later questions depend on. Two more habits make a big difference. When the tutor pushes on a summary you have just given, look for where it breaks down rather than defending it. And finish by saying what the data can't tell you. Lesson 7 works through a complete example.

Two kinds of question follow rules worth knowing in advance.

• Estimates and calculations. Say your method before doing any arithmetic, state your assumptions with round numbers, work it through out loud, and check the answer is plausible and has the right units. If the method is clear and you slip on the arithmetic, the tutor will usually just correct the number.
• Designing a test. Say what you would compare, in whom, and what you would measure. Then deal with fairness (randomisation, controls, blinding), size, how long, and the ethics. See Lesson 3 for more detail on these.

The next lesson turns all of this into a preparation plan.