Your classmates don't say hello to you, which really shows that you don't have a good relationship with them for many reasons.

1. is too strict, education is not necessarily just criticism and discipline, it can be expressed in gentle words, and students should remember to praise their own small progress;

Students think you are incompetent, so it is necessary to give students a try from time to time. If they can't solve it and you can solve it with simple and novel ideas, students will naturally admire you;

Some of your behavior habits are despised by most students, so you should pay attention to your usual words and deeds.

There are many other factors that cannot be listed for the time being. Teachers and students need to have a good relationship. First of all, you need to treat them as friends and don't put on airs.