Natural Sciences Admissions Assessment (NSAA); 2x interviews.
Interview 1: physics problem, chemistry discussion; Interview 2: personal statement, kinematics/graph questions.
isaacphysics.org; revising for A Level science subjects; keeping up with science-related current affairs
When stuck on a problem, tell your interviewers what you managed to figure out so they can help you.
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: Maybe 2 hours.
Length of interviews: 15 mins or so.
Online interview: No
In my first interview, we first looked at a sample physics question and how I would approach the question. We then discussed a concept in chemistry, which was no harder than A-Level difficulty but required a good understanding. The whole interview was more of a chat than a test.
In my second interview, we started by touching upon a project I had mentioned in my personal statement, and we talked about the scientific concepts involved in that project. I was then given a series of situations and asked to draw and discuss graphs relating to the kinematics. Finally, I was asked to sketch graphs for some functions.
For problem solving, physics skills, and graph sketching, Isaac Physics (https://isaacphysics.org/) was by far the most useful resource.
For estimation, I found a short
Looking back over my notes for science subjects also helped, but I was doing that to prepare for my mock A-Level exams anyway.
I tried to keep up to date with scientific topics, in part so I could discuss recent discoveries if asked, and in part for my own interest.
UKMT questions, NSAA questions, Isaac Physics
My advice would be to not be afraid to ask the interviewers for help if you get stuck, and to mention where possible what you were able to figure out before you got stuck. Their help can then give you a tool that you can use for any similar problem.