"You have had five teachers in this subject so far, I believe. Naturally, these teachers will all have had their own methods and priorities. Given this confusion I am surprised so many of you scraped an O.W.L. in this subject. I shall be even more surprised if all of you manage to keep up with N.E.W.T. work, which will be much more advanced." — Professor Snape on the curriculum's instability

Due to the constant changing of teachers until the jinx created by Voldemort was broken, the curriculum of Defence Against the Dark Arts varied from year to year. Each teacher had their own priorities and way of teaching, and their own respective efficiency proportional to his or her beliefs and methods, such as Quirinus Quirrell and Dolores Umbridge believing that theories were enough (which were, in fact, more hindering), while the more effective Remus Lupin, Bartemius Crouch Junior (then disguised as Alastor Moody with Polyjuice Potion) and Severus Snape had a more balanced belief in theory and practical defence.

Sixth-years were supposed to be given demonstrations on what illegal curses looked like; it was only in the 1994–1995 school year that this was changed to the fourth year. Earlier teachers from the 1985–1986 school year for example, were considered highly incompetent and ineffective by most students, and as such, very rarely showed up to teach.

During the 1988–1989 school year, the renowned Curse-Breaker Patricia Rakepick was appointed as the Defence Against the Dark Arts teacher for that academic year. She proved herself to be a highly effective teacher of both defensive and offensive magic, having taught her students a wide variety of fascinating and useful topics during her lessons, to compensate her students for having learnt almost nothing in previous years. She even gave her select students private lessons in the subject, teaching them how to duel, in preparation for locating the Cursed Vaults throughout the Castle.

Bill Weasley

During the 1989–1990 school year, Bill Weasley was given permission by Albus Dumbledore to teach extra-curricular evening classes in this subject to students after graduating the school, due to the ineffectiveness of the teaching that year. He continued teaching these lessons in the 1990–1991 school year as well.[61] Olivia Green, a former Ravenclaw student, was later appointed as the DADA professor during that school year.[6] She had Jacob's sibling investigate the existence of the rumoured jinx on the teacher's post during the school year. She also had them help her research Nogtails for a planned lesson.