Who was stronger, Snape or Black, ultimately remained a matter of verbal debate. No one knew what had really happened that day.
However, given Professor Snape's consistently poor reputation, most people outside Slytherin sided with Sirius.
The reason was his first Defence Against Dark Magic lesson.
Here, it had to be mentioned that Black, in his role as teaching assistant, had been assigned responsibility for the first- through fourth-year classes.
The fifth through seventh years were taught by the somewhat steadier Professor Lupin, because the fifth- and seventh-year students faced major examinations. Results in the Ordinary Wizard Levels and Nastily Exhausting Wizard Tests carried considerable credibility.
Hogwarts was a seven-year school, unlike Muggle education, which was divided into primary school, secondary school, and university. But that did not mean the concept of progression rates in Muggle schools had nothing to do with Hogwarts. Take the Ministry of Magic, for instance: when recruiting for positions, the first thing it looked at was young wizards' wizarding examination results.
Although some young wizards had powerful connections, their grades still had to be passable. Failing more than half their subjects would be rather embarrassing.
So, in a certain sense, it was actually quite similar to progression rates.
As the only magical school in all of Britain, Hogwarts still had to submit its results to public scrutiny and compete with magical schools across the world. If parents were dissatisfied, it would lose students, and losing students meant losing talent. One change affected everything else.
That was getting off topic. Back to it!
The scene shifted to Black's first Defence Against Dark Magic lesson since taking up his post.
That day, the young wizards were still arguing about whether Snape or Black was stronger. Oh, it was mainly Slytherin battling the other three houses-verbally, that was.