I have been slacking for the last few days only doing 1 hour and giving up when i dont register the new information. I get very stressed and think to myself im going to get a u , and i am aiming to get c's in all my subjects. I need revision tips for biology and chemistry because im really struggling with them. Im a learner who remembers stuff by repeating the sentence over and over again. Lastly from tomorrow im going to force myself to revise ,how many hours should i do to get from a d grade to a c?