I think that one weakness that some teachers have is favoritism. Sometimes a teacher, especially the younger ones, will kind of stick with the more popular kids in order to stay popular themselves.
Another weakness is being one sided in their method of teaching. For example, history or politics. My daughters friend goes to a high school in which the faculty is a 80% liberal dems...which is fine for them, but they push all of their one-sided liberal-ness on these kids, in a way brainwashing these uninformed children to one side, rather than educated them equally, informatively and responsibly to the differences of all sides, making them aware and able to make their own informed decision. The children then come out of the classroom with a mind full of material that is completely biast. That is not "teaching" in my opinion.
Another weakness is being one sided in their method of teaching. For example, history or politics. My daughters friend goes to a high school in which the faculty is a 80% liberal dems...which is fine for them, but they push all of their one-sided liberal-ness on these kids, in a way brainwashing these uninformed children to one side, rather than educated them equally, informatively and responsibly to the differences of all sides, making them aware and able to make their own informed decision. The children then come out of the classroom with a mind full of material that is completely biast. That is not "teaching" in my opinion.