Another positive aspect is giving the kids a chance to do things in a larger group, since they don't have that opportunity at home. For instance, this semester, our co-op takes some time each session to do a little team-building exercise in which the kids have to work together to compete in a particular challenge. (The challenge this past week was to build the biggest cantilevering structure out of toothpicks and clay!)
Giving presentations (public speaking, book reports, etc) is high on my list of skills I'd like to see developed in my kids, and a co-op provides a good setting for that kind of practice. This past week, the kids in our co-op were each assigned the task of writing and presenting a news story (since they went on a field trip to our local news station a couple of weeks ago). It was fun seeing what the kids came up with!
Strider chose to be "Johnny Anchor" and he reported a "breaking news story" about a giant purple cloth that had suddenly appeared, covering the entire top of the Bank of America building in the city.