Natural Sciences Admissions Assessment (NSAA)
Questions based entirely on subject content: starting with familiar then applying in unfamiliar ways
Revised A-level content; Completed mock interviews; Watched interview videos on YouTube
Completing past papers and practice questions
Try your best to relax! It's an interview, not an interrogation - it's okay to get things wrong.
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:
Number of interviews: 1
Length of interviews: 25 minutes
Online interview: Yes
It was me and two interviewers. I don't think there was anything about my personal statement at all - they just went straight in with some problems to solve - (for chem) starting with a mechanism we'd done in school, then pushing it further gradually by applying the same mechanism with some unfamiliar compounds to make different products.
They'd ask the question, give me a minute or two to think and jot things down, and then ask for my thoughts - if I said something they found interesting or that was incorrect, they'd follow up on it to try and help diagnose where I'd gone wrong. It turned out that one of the questions they asked was one I'd seen in a video before, and I mentioned this, but we carried on with that question anyway.
Our school had
You might also want to watch some interview videos on Youtube.
Past papers & practice papers. While NSAA is multiple choice, it is mostly calculation questions, so practicing those from AS/A level papers is also useful.
Try your best to relax! It's an interview, not an interrogation - it's okay to get things wrong, and it's okay if you've forgotten an important formula that's central to answering the question (this happened to me too :P). Also, your interviewers aren't just looking for a correct answer - they're looking to see how you think, and how you unpeel the question they've given you. Just communicate what you interpret the question as, what methods you're trying to do to solve it, and if you can see what's not going right - if they need to, they'll help you along with a hint or two.
This is maybe a bit beyond the scope of this site, but looking into the future a bit it's perfectly okay to swap subjects around - even as a physnatsci (physical natural science) without bio A-level you can pick bio subjects in first year, and who knows, you might find something you like? (I've swapped from phys to bio overall in 2nd year)