A couple that I've seen:
Snape's questions to Harry in the first class are all OWL/NEWT levels.
Snape is a ineffective teacher.
On the first one, Hermione knows the answers and there is no indication that she read texts that far ahead of her level. She has been shown to read history books and she memorized her textbooks but not much else at the start of book one.
On the second, in the scene with Umbridge monitoring Snape's class she says " Well, the class seem fairly advanced for their level" It's a little hard to have a class "fairly advanced for their level" and not be an effective teacher. However, effective does not mean nice and Snape is anything but a nice person.
Snape's questions to Harry in the first class are all OWL/NEWT levels.
Snape is a ineffective teacher.
On the first one, Hermione knows the answers and there is no indication that she read texts that far ahead of her level. She has been shown to read history books and she memorized her textbooks but not much else at the start of book one.
On the second, in the scene with Umbridge monitoring Snape's class she says " Well, the class seem fairly advanced for their level" It's a little hard to have a class "fairly advanced for their level" and not be an effective teacher. However, effective does not mean nice and Snape is anything but a nice person.