How can I revise?

So in my first year of A levels, I sucked at everything I did, in class I understood everything we were going through, but the problem came to revising and retaining the stuff I've learnt throughout that entire year. The subjects I take are Biology, Chemistry and Maths. If there is anyone who could help me, please, because I've failed everything I've done and I really want to turn everything around. Please help.

I'll tell you how i revised this year, i too just finished my AS year. At the start of the year i wrote very brief notes in class and then i would expand on them at home and type them. Every weekend i would go over my notes by reading them amd then on a sunday i would pull up the specification and annotate it with everything i could remember. At the end of every half term i would bin and delete all my notes and type them up from memory by just looking at the specification to stimulate my memory. It worked and i ended up with AABC (The C was in maths so that doesn't count and the B is getting remarked 😂). Hope this helps.

So really what you need to do is find a system that works for you, you should not revise during weekdays. So;

Monday - Friday (Note taking)
Saturday (Read and correct any notes)
Sunday (Some sort of revision, for me just annotating the spec and answering a few questions)