Hi armymom, and welcome! I think small versus large may not always be that important. It really comes down to the teacher and how they are able to accommodate your kid. It sounds like the current teacher is not doing such a great job. I would recommend touring the other school options and asking questions about how they differentiate for kids who are ahead, and whether they have other kids working at the same level as your kiddo, and whether they group those kids (clustering).
As KJP said, you may want to start considering grade acceleration if your DD is advanced across the board in all subjects. Even if you find a teacher who is pretty receptive and good at differentiation, it gets harder the more grade levels ahead the kid is. And if she is accelerated a grade, she will have a better chance of having intellectual peers. I recommend talking to the teacher a grade ahead at the current school and the other options.
Also, does the district have a gifted coordinator? He/she may be able to help with testing and with selecting a better fit teacher. Good luck!
