I am a Senior teacher. I have two years before retirement. I have taught a grade level for many years. Before school was out, I had my exit evaluation interview with my supervisior and was told I would be in the same grade for next year. Two weeks after school was out I received an e-mail on a Saturday from my supervisor stating I would be moved to another grade level and to contact her regarding the change. I called on the Monday. She was in a meeting so I left a message. No call. Then I went out on the Wednesday, she was not there. I left another message. No call. I went out again the next week , she was not there. I left a written message. She finally called. She stays the move is based on test scores. She needed a strong another reading teacher on that grade level. There are six teachers on this grade level all are experienced teachers for that grade level. There was little discussion abou the change because she had already made up her mind. She even told me she had already added my name to the third grade roster and she had no where else to place me. I know supervisors have the authority to move but can a supervisor that has given you their word that you will have one grade and then change you without any discussion after school is out be made to keep their word to that teacher?
In answering this, it should be noted that different schools and different school districts have different policies. Prior to any exploration online, I would check with your Human Resources department. If you are a member of your Teacher's Union, or if you have some type of collective bargaining association, I would be in immediate contact with them, as well, to gain their insight. Reaching out to both of these domains will provide a more focused and relevant answer because it is in your immediate realm. At the very least, in reaching out, your voice is heard.
Speaking with this in mind and from a theoretical perspective, the short and awful answer is that your principal does have every right to go back on her word. It's not pleasant, but from a professional standpoint, she has her ground. My guess is that upon the completion of your exit interview, the understanding you had with her was verbal. Even if you were able to sign something, it would be a letter of intent that speaks to you having a position for the upcoming school year. Wherever that position is becomes her discretion and she is able to do that as an administrator. It is not guaranteed. Administrators are always able to invoke the idea that they are acting "within the building's interest" and that staffing concerns are always fluid. Nothing definite in terms of placement can be assured as these situations can always be depicted as ones in constant change. This is where their authority can always be wielded. In short, she does have the right to do what she did.
I don't think it would be a bad idea to try to find some time and speak with her about how the move might not be in the best interests of the education of children. Teachers work best when they feel the most comfortable with the curriculum and the age group. It might be in the best interests of all parties possible if you remained where you were because it is such new terrain for you. It might not hurt to emphasize this, but if the principal has her mind made up, I think that the issue might be regrettably solidified.
It is a very difficult condition to find yourself. It is terrible to say, but if it is already decided, I see no other choice but to use the summer to really focus in on the skills you will need in the new position. In the final analysis, the principal's decision is not going to stop you from being a quality educator. It is regrettable that your voice has not been validated in this process. I would suggest that your craft is where your voice can be validated. Using the time in the summer to ensure that you are ready to take this one last challenge in your career will help in both the process of providing a capstone to your time in education and help your incoming students be stronger after a year of your instruction.