Write down specific times and instances when the teacher has been mean. You must be able to prove that your student is not simply whining.
Seek out administrative support to handle a vindictive teacher. Meet with the principal and the teacher in question.
Attend the meeting and bring your documentation. Remain calm and explain your child's problems to the teacher. Refer to your documentation and be specific.
Ask the teacher what he or she will do to rectify the situation. Often the teacher was unaware of the effects of his or her behavior and wants to make is or her students comfortable.
Offer to help in the classroom to alleviate some of the teacher's stress.
Have your student moved to another class if the teacher refuses to change or becomes worse.