Professor suspected AI-powered cheating on take-home midterms, makes finals in-person — only two students scored within 10% of their midterm score

Brown University professor Roberto Serrano suspected that his students were cheating when he gave them a take-home midterm exam, so he decided to make the final exam in-person. According to Inside Higher Ed, out of the 86 students enrolled in his class, 18 dropped from the class after he made the announcement, and nine skipped the final exam. Out of the 59 remaining students, three scored zero, and only two students received a grade that’s within 10% of their midterm score, with only one of them performing better in the finals.

Prof. Serrano, who taught Welfare Economics and Social Choice Theory (Econ 1170), usually conducted in-person exams for his class. However, the mass shooting on university grounds that happened last December made many students anxious about staying in classrooms, so he thought that it was just appropriate to let them take home exams. When news spread that the professor had such an arrangement, enrollment for his class ballooned to 86 students — more than double the usual 30 that he teaches in a particular semester.

The first sign of trouble came when he gave the take-home midterm exams. “Historically the average grade in the midterm of this course has ranged between 65 and 80 [percent], and this exam was harder than the exams I wrote in the past, because … take-home is an opportunity to challenge the class a little bit more, given that you’re giving the students unlimited time,” Serrano said, according to the publication. But this time, his class scored an average of 96%.

While some of the students might argue that he just happened to have a particularly gifted set of students this semester, the professor said that most of the answers were “kind of correct, but very off, and with a very convoluted style.” While they were technically correct, Serrano suspected that they were sourced from AI, especially after he ran the test through ChatGPT and received similar results.

Because of this, he emailed the class telling them about his suspicions — he made the final exam in-person and said that if the distribution is similar to the midterm exams, then he would count it towards their final grade. Otherwise, the midterms are void, and he’ll “reweigh the final accordingly.” But, as the data showed, it seemed that the majority of the class used AI during the midterm exams.

Prof. Serrano raised the issue with the university’s Standing Committee on the Academic Code, but it seemed that it didn’t take action until the story broke. Now, it seems that the university is going to review each case individually. In the meantime, Serrano is worried about the future. “We cannot afford to have a society in which a significant fraction of our best young minds think that cheating is OK,” the professor said to Inside Higher Ed. “That leads to a declining society, to a failed society … We cannot choose to become idiots.”