For a subject like chemistry, I feel that it's essential to truly grasp an understanding of concepts and not settle for a shallow/memorised understanding of the knowledge. I think that generally, kids tend to think that if they study more, they'll do better, or that simply rereading notes will help them grasp more information. However, this tends to create an illusion where familiarity is mistaken for mastery. For a subject like chemistry, which has a focus on conceptual understanding, I believe it would personally be best to study through working with a type of feedback loop. For example, study a bit on a section, then try to recall that information with worksheets, etc., then later try again and actively switch between revising the content and then retrieving it. Typically, the harder it is for something to be recalled, the stronger it will establish itself in long-term memory. So, probably don't focus so much on grasping all the content and then revising, but do it bit by bit and switch between revising and retrieving the information. Another thing might be to view chemistry more holistically and try to connect newly learnt information with the knowledge you have already acquired, as this makes it easier to remember/understand information, as it reduces the load on your memory (e.g. if you find a connection between mod 5 and mod 6, when you think of something mod 6 related you may also be able to remember something from mod 5 due to the connections you have established) and creates better memory traces. Take, for example, when you learn integration, it's simpler to understand as you'd probably already know that it's the reversal of differentiation (something you would have already learnt) as compared to if you were learning integration without knowing what diffing is.
Main things I'd recommend are actively switching between learning information and retrieving it, and doing so consistently AND to find connections and think more holistically to improve your own understanding and reduce the load on your brain to retain information.
