It's mean to prohibit someone from leaving your class.
Maria, a biology teacher, is overseeing a standardized test, and a student wants to leave for a bathroom break.
Maria wants to respond to the student.
Maria looks at the clock and decides to give the entire class a ten minute break.
Maria reminds the student that leaving the classroom will result in them failing the exam.
Maria uses the break to buy herself some coffee which gives her energy for the rest of the day.
Maria's reputation suffers when the students in the classroom give her bad reviews on the internet.