So. I'm basically being accused of plagiarism in my programming class right now. Another student and I had contacted the department chair with some concerns about how our professor was teaching the class. I won't go into the specifics, but we were informed that there were at least several other groups that shared similar concerns. And...now my grading rubric for an assignment says that my solution was "identical" to another student's, so I lose 25%.
Needless to say I'm pretty stressed about this.
Obviously I don't know the proper procedures at
your school, so take everything I'm about to say with a grain or two of salt. This is from my experience as an adjunct instructor at three separate universities/colleges, and five years in high schools.
First, if your prof says your solution was identical to another student's, he should be able to provide proof. I spent many hours making copies of identical papers, and many more hours explaining to students, department chairs, and, at the high school level, parents**. If he has no proof and still will not change your grade back, this is a separate complaint to take to the department chair.
Second, if the department chair hasn't been as responsive as you would like to your previous complaints, you need to go further up the chain of command, as it were. It sounds like your concerns were... placated... and possibly not taken seriously--it's hard to say. Certainly the department chair should respond to your complaint about the "identical" charge if the prof has no copies and no evidence.
At most universities, the next step is to contact the dean of the college. To go to that level, you need to make sure everything that has happened so far is
written out, ideally typed as though it were a lab report or the like. Your university may have a formal complaint system that you will need to navigate, so please check your student handbook to be certain you're following the proper procedures.
**The worst one was a year and a half ago, when a student turned in a lab report that was literally identical to a report from a previous year's student. Down to data that matched what the previous year's student had measured, as opposed to what his group had measured. In that class, the students turned their work in electronically, so it was impressively easy to catch and prove. Amusingly, this is a student who I had taught nine years earlier at the high school level... and had behavior and general academic problems at that time. It was sad to see that nine years, including seven in adulthood, had failed to significantly change his attitude toward schooling. (He received a zero for the lab and ultimately failed.)