Websites

Hi
I was wondering if any of you knew if some good websites where you can study all type if science but mostly chemistry an physics? I really have to study because I used to be really smart and get As but now I’m not thr smart any more an really need to up my game so do any of you know some good websites? All answers appreciated thanxx

just search at google… there are a lot of them.
personally. i think just spend more time studying the notes