A level product design helpWatch
Flashcards are useful for properties of materials and definitions such as the definition for tensile strength.
I would suggest picking one specific metal, wood and plastic to learn in detail - one that you think you could use for the vast majority of situations. This means that you don’t have to revise in detail for so many materials and also you’ll be really good at that specific one.
There are loads of quizzes on the internet about product design which could be useful to use.
Also make sure that you revise the later things in the spec because whenever I’m revising I always seem to start back at the beginning so I know a lot about materials properties and not much about anything after half way through the spec.
I hope this is useful in some way. Good luck.