it happened to my dd1,and she is nearing the end of her first year and has loved it.
when the school told me she was in a different class away from her friends she had made and the security, i was devastated, she was fine about it.
when the term started again for a new year i was so worried as she never knew the kids like in reception, all her mates trotted off to their class ans my dd, well she trotted of to hers with not a care in the world.
the way we handled it was i never ever showed my dd tht i was upset, i beefed the whole thing up to be a great thing, and made out she was special for being moved, i also said that she would have loads of friends as she kept her old ones at playtime, and made friends with new ones in class.
all positive in my opinion, makes them independant, imagine being with the same people all through school, it gives kids a false sence of security.
mix em up, thats what i say.
the only negative.....tons of parties!!!!