The twins are in pre-K this season, but since they were almost two when the first season started, they should be about six in this fourth season. Ally's age was knocked down two years in this season, also. They must have wanted the kids to stay a little younger. (edit)

Frank: (about Michael being held back) Hey, we thought that holding little Ray back wasn't such a big deal, but who's to say? You could have been a year ahead in your life right now. That car you've been saving up for, you could be driving it today! You could have married Debra a year sooner, had the kids a year sooner, which, for your information, would put Michael on the right track, and we wouldn't be having this conversation!
Debra: All right, now you listen to me, Frank! You want to help the kids? Then why don't you start by setting a decent, moral example? None of this matters, do you hear me? They're four. We just want them to be happy and healthy! (edit) Debra: That was the school principal on the phone.
Ray: And?
Debra: And they think Michael should stay in preschool another year.
Ray: Oh. And Geoffrey, too?
Debra: Mm-hmm.
Ray: (long silence) Well... that's okay, right? It's just like what we talked about. We want them happy and healthy. (pause) We still want that, right? (edit) Debra: Look, if it bothers you so much, think of it this way: Michael is the way the twins should be, and Geoffrey is exceptional.
Ray: Geoffrey's your favorite, isn't he? (edit) Ray: You left me back?!
Marie: Left back for love.
Frank: That and you were slow. (edit) Miss Sarah: Girls just often mature faster than boys.
Debra: But Geoffrey's developing on schedule.
Ray: Oh, my father will love that.
Debra: What are you...? Shut up!
Miss Sarah: Excuse me?
Ray: No, it's just that my father thinks that Geoffrey has...you know, homosexual tendencies. (edit) Miss Sarah: Michael just lacks some of those fine motor skills, and he seems reluctant to try.
Debra: Well, why do you think that is?
Ray: Yeah, is he stupid or something? Cuz if that's it, you should tell us! (edit) Ray: I want the boys to move up to kindergarten with the other children.
Marie: Oh, other children are overrated! (edit) Robert: Michael might be held back in preschool another year.
Frank: What, is he stupid or something?
Debra: No one is stupid here, Frank! Michael's just a little young for the class, and besides girls mature faster than boys.
Frank: Well, I guess that means Geoffrey's fine, then! (edit) Geoffrey: If you're American in the living room, what are you in the bathroom?
Michael: European! (edit) Ray: Why can't Michael be like Geoffrey? Gosh, you can't even get good twins anymore! (edit) Ray: Am I stupid?
Debra: If this is your new way of asking for sex, then yes. (edit) Ray: Look at how Michael cuts paper.
Robert: So... we hate him now? (edit) Debra: Ray, I think it's better if Michael doesn't associate cutting paper with you foaming at the mouth! (edit)

Apparently, the school decides at Christmastime that it's best to keep the twins in preschool for an extra year. Why would they be determining the events of the following year now, before the kids have had a real opportunity to develop and improve? In reality, teachers do not begin official assessment until January, and in that case, the twins have not had a fair chance to be considered for kindergarten next year. Kids tend to learn and produce a great deal from January to May, especially at this age. (edit) When Ray is in the kitchen with Michael at the beginning of the episode, helping him cut paper, look closely at the little actor playing Michael. There is a brief moment where he looks directly at the camera. (edit)

This episode does not have any allusions. Add some now!