How are classes/teachers decided?

[Earlybird]

DD is almost done with reception, and today all the children were taken to meet their teachers for next year. The children in the three reception classes have been shuffled around, so dd is with 6 or 7 from her current class, but the other children are different/from other classes. It appears that they tried to keep "special friends" together, but other than that, I'm curious to know how/why classes are mixed. Also is there any rhyme or reason as to which child gets which teacher? Anyone have any experience/insight?

Vlasses are purposely mixed up to help develop social skills and cope with change.

Classes are usually mixed up for a variety of reasons - maintaining a balance of gender, ability, SEN and social mix (these can change over a year, with movement of children, and especially after Reception when the children coming in were a fairly 'unknown' quantity).
As to which class gets which teacher... again, that's down to lots of different reasons, although I doubt one child's needs are considered in the decision, but they do look at the cohort as a whole. Sometimes a more experienced teacher will be given a more 'difficult' class. Sometimes a teacher will have requested a particular age-group as part of their own professional development. Sometimes teachers are put in classes because that is what the Head has decided, for their own reasons.

Every school will be slightly different, I imagine.

Ds was at an International school abroad until last summer where it was based on a mixture of keeping 1 or 2 close friendships, separating obvious personality clashes, spread of academic ability and English as a first language, and balance of sexes. Because the turnover there could be up to a third a year the classes did shift around quite a lot each year.