Will they be in the same class for both years, or move to a new class?

My daughter is in preschool this year, and will go again next year. Her class is 3 and 4 year olds, and she just turned 3 before the school year started. I always assumed she would move to another classroom, because there are other rooms in the school...but now I'm not sure? She fits the criteria for her current room, so I'm curious now...