I attended private school until the second semester of my freshman year, before moving and attending a public school. After a while, I did make a lot of good friends that were very similar to me.....basically a quiet group of really good girls that didn't have boyfriends, made straight A's (you know the type). BUT, when I first started at the public school and I was still meeting people and trying to see where I fit in, I met some really different people. All very nice and I'm thankful to everyone and their kindness to me, but it was an eyeopener! I was so shocked to find out that kids my age were having sex and doing drugs. I know, perhaps I seem naive, but that was something I was never exposed to in the private school.
Not telling you this to make you worry about public school, but I just wanted to give you a heads up that there seems to be a lot more diversity in a public school, so hopefully your kids will quickly settle in with kids that are similar to them in terms of values, beliefs, study habits, etc.