We've had a couple "Chamber Days" since Halloween, and another this week. Then our concert is on Monday, the 16th. After that, we'll take the next two days to rehearse those small ensembles, then take the final two days to have them perform for the class. We will talk about concert etiquette and also invite any parents who are available to come watch. Students are required to dress up, too.
This year, I bought a classroom set of the new small ensemble/trio books by Jack Wilds, Three For All, published by FJH Music. You can mix and match parts and instruments, so splitting into small groups is pretty easy. Our percussion section is playing two small ensembles from Beyond Basic Percussion from Tapspace.
Even though I assign each group a different piece (so there are no duplicates on the concerts), they are welcome to try others from the book if they have finished working up their assigned piece.
I float around to each group and listen while offering suggestions and making sure the students stay on task. I'm always surprised to see who steps up as a leader and how they figure out how to start playing. I'm also intrigued by how they choose to set-up their ensemble, but often will reorder them because they didn't think about putting like parts together, etc.
Our students learn so much about music making by doing this. Things like intonation, style and balance suddenly really seem to matter a lot more when there are fewer students present and they can actually hear the inaccuracies... I can think of several very prominent HS Bands in Texas who do a lot of chamber work because the benefits are so clear and pervasive.