The claim that marijuana can help you study is exaggerated. Marijuana is usually not seen as beneficial when it comes to study habits and studying. especially if you're trying to retain information, focus, or stay motivated. However, there may be specific situations in which ingesting marijuana could be seen as beneficial, such as suffering from or managing anxiety.
Research has proven that Marijuana impairs short-term memory, and when ingesting marijuana, you could be at risk of negatively affecting your learning capacity. This making it harder to absorb new material.
Marijuana decreases attention span. Cannabis use is associated with lower attention span and slower information processing, which is very important when it comes to studying. If you are unable to stay focused and recess information into your long-term memory (LTM), you are less likely to be successful with remembering information for your exams. The National Library of Medicine explains, "This profile of effects suggests that cannabinoids impair all stages of memory, including encoding, consolidation, and retrieval. Several mechanisms, including effects on long-term potentiation and long-term depression, and the inhibition of neurotransmitters".
In the article Leafwell, they discuss the potential benefits of using cannabis while studying. They claim that CBD could help with energy levels, but they then express that this isn't guaranteed, and most people experience fatigue after ingesting marijuana.
So while some people may believe marijuana is beneficial to studying, it is not helpful for memorization, comprehension, focus, and it is not recommended while learning.
Crean, R. D., Crane, N. A., & Mason, B. J. (2011). An evidence-based review of acute and long-term effects of cannabis use on executive cognitive functions. Journal of Addiction Medicine.
Ranganathan, M., & D'Souza, D. C. (2006). The acute effects of cannabinoids on memory in humans: a review.Psychopharmacology.
Leafwell. (2023). Does cannabis help or hinder studying? https://leafwell.com/blog/study-on-cannabis