Studies have shown teaching material is the best way to learn it, a process I’ve written about before. The act of clearly explaining something, even to an imaginary student, engages a different part of your brain than just absorbing the material. And here’s some more science, a meta-analysis of 64 studies involving 6,000 students, all showing that the ability to explain something (even to yourself) leads to better learning outcomes than when the explanation comes only from a teacher or book.
If you want to raise your grades this year, put some teaching into your studying.