Each summer we sign our 7 year old up for the Alameda Parks and Rec summer aquatics program at the Encinal High School pool. Usually he does two of the three sessions, covering 6 weeks, with lessons four nights a week. At the end of each session they issue a report card and let the kids know the level they are on.
There are actually two pools at Encinal High, a fairly shallow one and one that is set up for lap swimming and diving (it has a spring board in one corner where the depth increases to 12′).The shallower one is heated, and is where most of the classes happen. The deeper one is used by the groups on the higher levels and for treading water by the lower groups (it has a shallow side).
The lessons are relatively small groups (five or six kids per group), and the instructors look like college or high school kids. There seems to be quite a bit of variation in what they actually do between instructors, but they do spend the entire time working with the kids. The last five minutes of each class are a free swim / play time for the kids too which they like.