Cambridge Natural Sciences interview

The Cambridge Natural Sciences interview is academic and mostly problem-based, on subjects you've already studied, taken somewhere new. For the Physical stream, that means unfamiliar maths, physics and chemistry problems, worked through out loud while the interviewers watch how you reason and use their hints. Physical applicants usually have two interviews of 20 to 30 minutes, often one maths-led and one on physics or chemistry, in December 2026 (main period 7 to 18 December). Whether they're online or in person depends on the College.

Key facts

What happens in the interview

Natural Sciences interviews are "not a memory test". They're on what you've studied, taken somewhere unfamiliar: questions often involve deriving a function and exploring its behaviour, or a familiar idea in "an unfamiliar guise". Any area of your school maths and science can come up, not only the topics you said you liked.

Your choice of the Physical or Biological stream, and what you're studying now, shapes which interviewers you see and what they ask. Physical applicants commonly have one maths-led or general physical sciences interview and one on a subject, physics or chemistry. Some Colleges set a short preparation paper to discuss, and some give a single longer interview instead.

Interviewers run it like a supervision, friendly and informal:

• They give a hint when you're stuck and see what you do with it.
• They ask why, and ask for a sketch or an estimate.
• They check units, limits and special cases.
• They change a condition.
• If you get something straight away, they move on.

Not finishing is normal, and you can ask for clarification at any point.

You'll work on paper, or on a drawing tablet online, and may be asked to share your working. Have paper and a pen beside you, or a drawing tablet if your College asks for one (Trinity requires one online). For practice, St John's suggests the more advanced problems on Isaac Physics, and Christ's points there too, including its chemistry questions.

What interviewers look for

Natural Sciences interviewers look for:

• The ability to analyse and think through scientific problems from principles, including a familiar idea in an unfamiliar guise.
• Mathematical fluency: questions often involve deriving a function and exploring how it behaves.
• Physical and chemical intuition.
• Motivation and intellectual potential, rather than stored facts.

Toby's practice interview scores five criteria: mathematical skill, scientific reasoning, scientific intuition (predicting what a physical or chemical system will do, estimating sizes, and judging when an answer is plausible), explaining your thinking, and motivation for science.

How the interview is marked

Cambridge doesn't publish a marking scale for Natural Sciences interviews. Colleges weigh the interview together with the ESAT, your grades and the rest of your application, including your reference and personal statement, in a holistic assessment.

Anyone can have an interview that doesn't go to plan, and a bad interview isn't the end of an application.

Example questions

These are problems published by Cambridge and Oxford sources, in the form Toby asks them: one each for the maths-led, physics and chemistry interviews. Interviewers set their own questions, so yours will differ.

Sketching x over (x − 1)²

Published on a Cambridge Physics (Cavendish Laboratory) page: Physics and Maths for Natural Sciences sample paper

Sketch the curve y = x/(x − 1)² for −∞ < x < ∞. Talk through the main features as you go.

• Why interviewers ask it: it shows whether you can build a sketch from intercepts, asymptotes, signs and turning points, and read the answer to an algebra question off a graph.
• A hint an interviewer might give: "Where does the curve cross the axes? And where is it undefined?"
• A strong answer collects the key features before drawing anything: where the curve crosses the axes, what happens either side of x = 1, how it behaves far away and where the gradient is zero.
• A common slip is drawing the two branches at x = 1 going in opposite directions, as they would for 1/(x − 1).

Mass of the atmosphere

Published by Oxford: sample interview questions

How can we estimate the mass of the atmosphere? We can't put it on a scale, so think about what we can measure from the ground.

• Why interviewers ask it: it shows whether you can find something measurable that answers the question, then estimate cleanly and check your assumptions.
• A hint an interviewer might give: "What does a barometer actually measure?"
• A strong answer works from a quantity measured at the ground, keeps the units consistent, and checks its assumptions, for example by comparing the depth of the atmosphere with the Earth's radius.
• A common slip is trying density times volume, with no sensible way to choose the height.

Six carbons, twelve hydrogens

Published by Oxford: sample interview questions

How many different molecules can be made from six carbon atoms and twelve hydrogen atoms (C₆H₁₂)? Don't worry about a final number yet: what kinds of structure are possible? Draw a few.

• Why interviewers ask it: it shows whether you can picture molecules in three dimensions, organise a search so that nothing is missed or counted twice, and recognise new kinds of isomerism when prompted.
• A hint an interviewer might give: "How many bonds does each carbon want to make, and each hydrogen?"
• A strong answer uses the bonding rules and a formula you already know to work out what kinds of structure are possible, then organises the count systematically and checks for duplicates by naming each molecule.
• A common slip is drawing the same molecule twice, flipped or numbered from the other end.

Practise with Toby

Toby is an AI interviewer that runs practice interviews by voice. The Cambridge Natural Sciences interview is built from Cambridge's admissions pages, the Natural Sciences Tripos pages and College admissions pages. It covers the physical sciences only: biological sciences interviews aren't covered yet. Most candidates have the maths-led interview plus a subject interview in the science they're studying:

• Maths-led interview. Maths-led problems, often in a physical setting: deriving a function and sketching how it behaves, calculus, series, approximations and probability.
• Subject interview: physics. For candidates studying physics: A-level physics taken somewhere new, from forces, orbits and oscillations to waves, circuits and heat, with sketches and estimates.
• Subject interview: chemistry. For candidates studying chemistry: A-level chemistry taken further, from bonding and energetics to equilibrium, rates, mechanisms and spectroscopy, reasoned from principles rather than recall.

It draws on 53 problems, each with hints and follow-ups. Seventeen are published problems from Cambridge and Oxford sources, and the rest were written to the same style and level, with every result independently re-derived.

Toby puts the problem on screen, gives you time to think and asks you to talk it through. He gives a hint only when you're stuck, asks why, asks for a sketch or an estimate, and changes a condition to see if your reasoning holds. Like a real interviewer, he doesn't praise every answer.

You can add your personal statement so Toby can ask about it, and choose a 10, 20 or 30-minute interview. Your prep page has the format, what interviewers look for and practice problems with hints and worked solutions. Afterwards, your debrief gives you a practice mark out of 10 (6 is acceptable, 7 good, 8 strong), a score against each criterion, notes on every question and the full transcript. A practice mark is a guide, not a prediction.

Frequently asked questions

Sources

Last checked October 2026.

• University of Cambridge: Natural Sciences
• University of Cambridge: Interviews
• University of Cambridge: Preparing for interview
• Natural Sciences Tripos: Admissions
• St John's College: Natural Sciences (Physical)
• Christ's College: Natural Sciences
• Cambridge Physics (Cavendish Laboratory): Physics and Maths for Natural Sciences sample paper
• University of Oxford: Sample interview questions

Related interviews

• Oxford Physics interview
• Cambridge Engineering interview
• Cambridge Mathematics interview

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