It is a mixture of both appreciation and ingratitude, some teachers who are kind and serve their time towards their students with full determination without doing discrimination in them are appreciated and they deserve that. On the other hand, teachers who are cruel, full of attitude and do not give time to students, lacks their determination in serving students are never appreciated as they don’t deserve that so if we interact with those teachers whom we love to interact share all good and bad things about teachers.

To answer this question, you may talk about the following points.
Is it so that a student might be friendlier with one teacher than another one?
What are the qualities that make teachers a friend of a student?
Are students afraid of talking about a teacher to another teacher, knowing that they are colleagues?
Do students take the problems they face with one teacher to another teacher in the hope for a solution?
Does a student try to be respectful towards his/her teacher while talking about him to another teacher?