I personally believe there is no spell out there to make you do good in school... But, I suggest doing what I did. I went to a metaphysical store and bought myself a mojo bag that was related to helping you do well in school and focus on your studies a lot better. I also bought Rosemary incense too that helps you focus on your studies. Just study with a little push like lighting Rosemary incense.
If you can't find a metaphysical store located near you, I know a lot of head shops and smoke shops sell different kids of incense. My friend works at a smoke/hookah shop and that's how I got to buy a lot of incense such as dragon's blood, cinnamon, musk, etc. But, you have to be at least 18 or older to even go inside... Unless the people who work there are cool with it.