Natural Sciences Admissions Assessment; 2x Interviews.
Interview 1: chemistry questions; Interview 2: physics questions.
Revise A-level content and ask teachers to ask you interview-style questions.
Do past papers under timed conditions.
Stay on top of your A-level content and think out loud in the interviews!
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: 2
Time between interviews: 1 hour
Length of interviews: 10-15 minutes
Online interview: No
My first interview was on chemistry, and started up with a nice subjective warmup question which they then turned into a more interesting question to see how I coped with new material, as the topic they asked about isn't covered until halfway through the first year of university! They then asked more chemistry questions. The interviewers were very nice and made sure I felt comfortable, and were very helpful when I got stuck on topics I hadn't covered before. It was a nice relaxed atmosphere and I actually really enjoyed it! My second interview was physics and started off with some relatively easy calculus questions, before moving onto some really fun "real world" type questions. Again the interviewers were lovely and really encouraged me to give everything my best go and again I had a lot of fun. Neither interview had questions about my personal statement, and I'm pretty sure they hadn't read it as my first interviewers didn't know I'd taken a gap year, though I don't think this is common.
They can't test you on anything you wouldn't reasonably be expected to know, so just brush up on what you've covered in A-level courses so far, and don't sweat the rest. If you can get a teacher to ask you some interview-style questions that does really help you focus on what to improve.
I was in the cohort of the second year to do the test, so there was only one past paper and one sample paper available, which meant I couldn't do much preparation with past papers. Nevertheless, the past papers I did were really useful, especially doing the papers timed as time pressure is a big factor in the NSAA. Other than that, just make sure you know your A-level content well, especially maths as it comes up a lot. And try to be accurate as there are no working marks for multiple-choice questions.
Just make sure you're on top of your A-level content as that is what they'll be looking out for. Take your time to talk through your thought process when answering questions; the interviewers are more interested in this than how quickly you can answer their questions. Above all, just try and enjoy it as it's a really special experience and can be really fun!