Interest in the subject, recursion-based puzzles, and asked to apply the same idea in more and more difficult ways
Books, open days, wider reading, spoke to family, mock interview
Practice papers, UKMT
Relax and don't try too hard to impress them
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
Test taken: Mathematics Admissions Test (MAT)
Number of interviews: 4
Time between interviews: Stayed in Oxford for 3? days
Length of interviews: less than half an hour?
Online interview: No
There was usually one interviewer and one person watching, they might give part of the interview too. There were some small talk/questions about my background, interest in my subject, and basic CS knowledge, which I think were intended to relax me. I was asked to solve mostly recursion based (mathematical or visual/shapes based) puzzles, and asked to apply the same idea in more and more difficult ways. I found most of the puzzles really fun and a bit like the CS-only MAT questions. The best advice I have is to go in and try to enjoy yourself and act normally rather than actively trying to impress them - they will like you as a student or they won't. -When you get stuck, explain why you're stuck out loud and any ideas you have even if they're bad. I was always helped after a small amount of time being stuck. They don't want you to be perfect, they want you to be able to respond well to their hints and guidance. Ask any question you like (obviously not directly for the answer). I asked questions to clarify the problem, I asked questions when I didn't understand the help they gave me, I pressed them to explain why my own answers were wrong, I asked for further reading on my favourite question. I believe they like questions. They asked me what I expected to be on the syllabus which I really panicked and blanked on - do give the list of courses a skim! I quickly derived some small formulae when needed (eg sum of geometric sequence) which I think impressed them.
Had been reading some books about Computer Science ideas for entertainment, also went to 2 Computer Science related open days at oxford, made sure I could describe some of my favourite ideas from these to show interest. Read about some famous advanced topics (ML and P vs NP) so I could describe more complex CS ideas if asked (I wasn't though). Tried to brush up on my basic CS knowledge (e.g. stuff about languages, famous problems, applications) and prepare an answer for why I am applying to Oxford and why CS. Also asked my dad to "interview" me with the sample questions that Oxford provides for CS. Do anything you can to practise 'thinking on paper'/explaining your process to friends and family, if they have a mathematical mind and can push you properly then all the better. Attended a
As many practice papers as possible in the time - prior experience with UKMT (maths challenge) helped
I believe I succeeded because I was relaxed and not trying too hard to impress them (obviously I tried hard on the questions themselves). I said whatever I wanted to say, asked for help and showed my genuine enjoyment of the subject and curiosity. They are trying to choose a person they will be teaching for the next 2-4 years - you won't always be at your best during that time, they just want to know that you will generally be a good student. Show your real self.