Hi there. In this education post, I go over some cases where teachers can be unfair.

Examples Of Demanding Tasks Of Students
Here are some examples that I have experienced or heard of when it comes to homework load, test preparations and test demands for students.
Too Much Homework
There was this biology teacher for grade 11 and 12 in my high school who was known for giving out too much homework. The amount of homework was something like 1 hour per day. This does not sound like a lot but high school students have 3 other courses that could have lots of homework. I have heard some students complain about this homework load.
The biology teacher's reasoning was that in university you have lots of homework so she wanted to prepare students for university level biology courses. I guess this reasoning is okay.
Difficult Tests
Difficult tests can appear out of nowhere. Sometimes tests are made to be difficult to bring down the class average to an average that is preferred by the administrators or something.
There are some weird cases where tests are made to be impossible or near impossible. Some teachers enjoy making hard tests for whatever reason. There could be some questions that have topics that have nothing to do with any of the lessons or readings. I once was able to answer a question that was not covered in class or in any homework but I knew it from a previous probability course.
Short Notice Announcement Of Tests
I have heard from a few student clients I work with at my Mathnasium work that sometimes teachers give the announcement of a test 2 days in advance. The teacher could have no course outline for a course which keeps students guessing. At any given day, the teacher could announce that there is a test in two days. Two days is not a lot.
With this type of environment where the teacher can announce a test in two days, students should pay attention in class and regularly keep up in class. Short notice test announcements do punish those who don't do work until there is a test coming up. This is in theory.

Closing Notes
You never really know why some teachers do things that make things much harder for students. Some teachers may not be aware of the impact of their actions on students. Some teachers enjoy making students suffer or something.
There is a possibility that certain teachers are not very organized and may have poor time management skills themselves. They may not have the tests ready ahead of time.
There is also the possibility that the teachers could be told to make tests difficult out of nowhere.
Students who do well through tough times in school do develop resilience and grit. These are hard to develop and can help in future tough times.
