Which spirit should I contact or what ritual should I do?
Any spirit in regards to the faculties of the mind and learning. There are hundreds of versions to choose from so pick one from a culture that resonates with you and that you have a fascination with. I personally prefer Thoth because I love the Egyptian version and flavor. But id you like Mesoamerican Quetzalcoatl would be good or if you prefer Greek Hermes is a way to go and if you are a fan of the goetia there’s President Camio or if you’re the angelic type metatron. Pick the one you like the best they are all the same thing.
Well the obvious is work to change your grades. Spirits are great and all, but it still requires work on your end. They can’t change them for you - they can help you learn to change them yourself.
At the end of the day, your the one has to pass whatever class not the spirits.
The best ritual would be study, but there are plenty of spirits you can work with, that can help your learning along.
Any deity or spirit that rules over education and knowledge. Saraswati and Athena have helped me with this but made sure I put in the work.
Spirits associated with the element of air are usually good study partners. Depending on your experience you can preform a ritual before studying or as simple as lighting a candle while studying. Many choices.
@Unknown_Person I recommend u check out this thread:
But as what Mindseeker said. U still have to put in work on your end!