First you need to understand that teaching is a chosen profession.  Teachers do not do it for the money.  They do not do it for the fame.  They do because they love children.  Classrooms are like a box of chocolates, you never know what you're going to get!!! Teachers are not mean, teachers are firm.

Teachers are not mean. They can become frustrated when a student continued to NOT follow the rules set before them that are repeated day after day for them to help remind them. Students need to get good rest, not constantly play games until wee hours of the night at home and then come to school exhausted. Students also  need to eat a proper meal to help their brains work to learn things they are presented with at school. Teachers only want the best for their students and that they succeed in school to help them be good leaders in the future. If a student is not doing his or her job, there are always consequences to those actions.