AM, AE and I attended our first Suzuki institute. It was a wonderful experience, and the girls learned SO much! They both had a master class, group class and a play-in every day. AE also had preparatory orchestra, and AM had music mind games class.
First of all, I think the biggest benefit for us, was teaching me how to work with them. All the instructors were fabulous, and I learned so much. My biggest takeaway was the 1-point lesson. I have read about it before, of course, but I think this was the first time I actually saw it in practice. AM really struggles with stretching her fingers on the cello for example. It is in part because the cello is a bit big for her (1/8th), but also because she can't see her fingers when she plays, so she forgets to spread them out. Her instructor tried quite a few tricks to get her to do that correctly, but ultimately, what worked best was telling her that she gets an "x" every time she looses concentration, and her fingers get scrunched up. The thing he didn't do (what I normally do when I practice with her) is yell out other instructions like "keep your elbow up" or "watch your bow hold!".
AE loved being in the orchestra. This was her first orchestra experience, and she requested to be signed up for one when we go home :) The class (Preparatory Orchestra) was very cute: it was more about following the conductor then playing music. The first piece they played was an improvisation piece, and they were supposed to play what the conductor showed them. The second piece was "Simple Square Dance". They had 3 violin parts (AE was first violin, but I don't think that was based on anything other than where they were sitting on the first day). It was cool, because all the kids actually did sound really good together! (Proud mommy moment :) )