Hi!
I'm a preschool special educator, working in an inclusive program, so I can give you some ideas about how things have worked in the programs I've been in. There are lots of different models of "integrated" preschool classes. From your discussion of halves and other things, I'm guessing that you mean a model where a school district either has or contracts for classrooms that serve approximately 50% children with special needs and 50% typically developing children, and that don't typically provide services to all typically developing children that age. I live in a district with pretty close to universal 3 and 4 year old programs, so the answers for me would be different.
As far as where do the normally-developing peer models come from. I think they can come from many places. In some places the other half of integrated classrooms are chosen because they are considered to be "at risk", they're children who have low income, or who speak a different language at home. Other places the integrated classrooms are open to all members of the community, either for free or for a fee. There's often a lottery. Some reasons why families might choose an integrated program for their children include: they teach at the school and want their children close, their older children attend the school and they want their children to be in the same location, their have other children who have attended or are attending the integrated program as students with disabilities and have fallen in love with the program, they feel strongly that inclusion benefits everyone, they know that integrated programs frequently have more educated teachers, they suspect their own child might need extra support but he/she isn't diagnosed yet or simply because the program is cost effective or happens at the right time and they want their kids there.
Do the parents know? If it's a situation where all the classes are integrated, especially at the 50% level, then it's almost always highlighted in parent tours or handbooks, and parents know that about the school before they make a decision. I know in the inclusive settings I've worked in (I'm using inclusive to mean schools where the majority of children are typical, and children with special needs are welcome as full members of the class and provided services within the classroom), we are very up front about our inclusiveness in those circumstances because we want parents who wouldn't be welcoming or comfortable to self-select another school. On the other hand, if it's a situation where the school has a number of non-integrated classes and one or two integrated classes, parents may not know until they are assigned, but the school usually communicates in some ways the situation.
Is there any friction between the two halves? I don't think that the children think of themselves as two halves. They are certainly aware that Johnny communicates with signs or that Mary uses a wheelchair or that if you want to ask Eve to play you need to say her name clearly and get her to look at you first before you invite her, but they don't attach any more meaning to that than they do to the fact that Suzie teeters around on the high heels from the dress up corner every day, or Joshua is an amazing tree climber. If they classify themselves into groups it's much more likely to be around preferences (e.g. we're the kids who like to play with the trikes and scooters) or gender or physical attributes including dress (e.g. Scott and I are alike because we both like to wear princess dresses all day at school, or we both have velcro shoes). Is there friction between parents -- generally not unless resources are scarce. Sometimes you'll run into a situation where there are integrated classrooms that aren't any better staffed than the classrooms of all typically developing kids. In those cases everyone is going to lose out because the fact is that special needs kids have more needs, and that usually results in too many needs for anyone to get all of them met, and you might find a situation where parents blame the children they perceive of as neediest. It's not fair but it does happen. So you want to hear that the school has an extra teacher, or a smaller number of children in their integrated classrooms relative to what they have in their mainstream classrooms. In those situations where everyone is getting their needs met there may be moments when there are misunderstandings that need to be cleared up, but I wouldn't say friction, just opportunities for increased communication.
Are there benefits to typically developing kids to being in integrated or inclusive classrooms? Yes, huge benefits. Children in integrated classrooms definitely learn more about acceptance, about social problem solving, and about not assuming that everyone is the same. In addition, teachers in integrated classrooms generally get more professional development. In my setting I frequently go into the classroom and tell the teachers -- here's something I'd do to benefit Johnny's fine motor delays, or to increase Josue's vocabulary, or to make it easier for Meredith to sit through circle, and when I come back they've applied that same technique to half or all of the class. Children with special needs also serve as a great weather vane. For example, if you're asking your kids to sit at circle too long, you'll lose a lot of them and learning will stop. Many times, however, the typically developing children will start daydreaming, or otherwise disengage in a manner that's not so obvious, and the teacher will continue instruction not knowing she's lost them. On the other hand, if there's a child with regulatory challenges in the group that child will make the fact that he's done with instruction known loud and clear. That's a strong incentive for the teacher to do things differently next time, which benefits every child.
Good luck! I hope you find the perfect class for your child!
