We strongly considered our local friends school. And looking more in depth, it looks ideal for a MG child that would do well in a small school environment. But it wouldn't be great for DS for more than a year. It is also very expensive.
The work the kids did there was quite amazing and they did so many great hands on science and comunity involvement type activities. The also did music, science, and spanish. If I had MG kids and could choose any school, it would be this school. I had no idea Chelsea Clinton went to a Friends school. Interesting.
My only advice is asking a lot of very specific questions and see if you can talk to any other GT families that have choosen the school. Spending a day (or more) in the school is a great idea.
