In school, some teachers will offer private tutoring classes. I have been told that these teachers sometimes let the exam questions “slip” in those extra classes, meaning those who pay for the classes know what to study for the upcoming exam, and thus get better scores. One tome, when I was in high school and got 100% in an English test, my teacher asked me in front of my classmates, “Which teacher did you tutor with?” despite the fact that I had always done well in English classes.