A college student was having a hard time with his math class, so he paid his brother to do the homework assignments for him. The student’s major is law, and this is a math class, which for some reason the college requires him to take, even though it is irrelevant to his major. Did he transgress, and if so should he go to the professor and confess and instruct the professor to lower his grade?
What the student did is wrong in two aspects. It is geneivas daas, because he fooled the teacher, and the school into giving him a diploma when he doesn’t deserve it. Worse than that is the it may also be outright geneiva because the person who employs him and paying him is only doing it because he has a diploma, (which he got dishonesty) and otherwise he would not have consented to hire him.
Regarding the teacher he does not have to technically ask him mechila because he didn’t cause the teacher any actual harm, but the issue of getting the undeserved diploma will remain.
Igros Moshe CH:M 2-30, Shevet Halevi 10-163.