BioEditGreendale, the study group decides on Biology 101 as the class they will take together for the semester. The instructor is Professor Marshall Kane, a former convict who earned his degree in prison. He was a very serious and no-nonsense instructor. Despite his intensity, he was capable of great insight and had a strong sense of justice, which he upheld with his own personal code of honor. Because of the fallout from an incident he was directly involved in, he ended up officially resigning from the school. His first appearance was in the Season Three episode "Biology 101". He is portrayed by actor Michael K. Williams.
Professor Marshall Kane is first introduced in the series when he is seen addressing his new students in biology class and giving them his first lecture of the year. He is interrupted when Jeff's cell phone goes off and tries to continue. After Jeff's phone rings a third time, Kane angrily tells him to leave his class. Later, Jeff apologizes for the incident and asks if he can return. Kane tells him he'll only consider it if he gives up his cell phone. Jeff is amused at what he thinks is a bribe, but Kane corrects him and tells him that his phone is a symbol of Jeff's own imprisonment. Just like the prison walls that kept Kane confined in prison for years, Jeff has built up his own walls to keep other people at arm's length; he adds that not even a single blade of grass can break through those defenses. Jeff scoffs at Kane's assessment of him and instead jumps to the conclusion that he and Pierce are in cahoots when he sees what appears to be a photo of them together above Kane's desk. When Jeff's assumption is later proven wrong, he sends the professor a gift as a sincere apology for his actions. The gift is Jeff's cell phone with a single blade of grass poking through it, a physical representation of Kane's appraisal of him. Professor Kane allows Jeff to return by ejecting Alex "Star-Burns" Osbourne from his class.
Sometime later, he arbitrarily assigns lab partners for all of his students. The study group is uncomfortable working with classmates they don't know and asks the professor if they can instead be partnered with each other. He agrees, but their first assignment proves a disaster. Their fellow classmate Todd had been forced into wasting an entire evening in Group Study Room F with the study group. They were arguing about who should be paired up with whom and who should be stuck with Todd. After hearing Todd's complaint, Kane compares the study group's behavior to his time in prison when he encountered a "mean group" that bullied other inmates. He informs them that from now on, they are all to share one grade together collectively. Towards the end of the semester, Kane receives a phone call in the middle of the night from Annie concerning her and the study group's yam project. The project had been ruined as the yam had fallen to the floor and was now squashed. Professor Kane sees it as an accident, but Annie insists that someone sabotaged it. Kane tells her there's nothing to back this up, and she takes it as a challenge to find evidence to support her claim.
Annie and the study group investigate the yam's "murder" and come up with evidence and an eyewitness in Star-Burns that points to Todd being the culprit. Jeff and Annie present this information to Kane. The professor asks Todd about the charges brought against him but before he can respond he is interrupted by a Lieutenant Colonel Archwood. He explains that he is Todd's former superior from his time in the military and is stepping in to act as his attorney. Archwood brings the situation to the attention of Dean Pelton and has a meeting with him, Jeff, and Kane to resolve the matter. Once there, Archwood immediately questions how reliable Jeff's star witness is as well as Star-Burns' own alibi for the crime. He also demands to know how Star-Burns came across the information which incriminates his client. Due to a prior agreement in exchange for his testimony, Jeff is unable to explain. When the Dean threatens to fail Jeff and the study group if he doesn't comply, Professor Kane steps in and states that as it's his biology class, only he has the authority to make that decision. He declares that he will allow Jeff's arrangement with Star-Burns to stand. Kane tells Jeff and Archwood they can both plead their cases to the class after which he himself will render a final verdict. Jeff thanks him for giving them a chance to get their grade back, and Kane simply responds that a man's got to have a code.
The next day in the biology lab, the improvised trial convenes, and Archwood has Todd on the witness stand. After he finishes portraying Todd as a national war hero, the prosecution starts their cross examination with Annie complimenting Todd as well. Archwood objects, believing she is leading up to something, and Jeff counter-objects to that objection. Annoyed at the antics of both attorneys, Kane overrules them and adds that he dislikes both of them. He tells Annie to proceed cautiously and reminds her that this isn't really a court of law. Annie then tricks Todd into admitting he was at the crime scene and had picked up and accidentally dropped the study group's yam. The revelation causes Archwood to abandon his client and leaves the classroom in an uproar. Kane declares he has heard enough, but before he puts an official end to the case, Jeff asks him for a sidebar to confer with him. Once he and Annie are inside Kane's office, Jeff asks the professor to just give both the study group and Todd a passing grade on the project. Annie is angry at his idea and takes Jeff aside for a sidebar of their own to berate him for suggesting such a plea bargain. Kane listens in on their conversation as Jeff explains to her that he isn't convinced of Todd's guilt; there seems to be more to the situation than they are aware of at the moment.