AltSchool is a collaborative community of micro-schools that uses outstanding teachers, deep research, and innovative tools to offer a personalized, whole child learning experience for the next generation. (Source: http://www.altschool.com). Schools in this network cater mainly for kinder and primary students with a few that go up to initial years of Middle School.
This link will take you to a recent article on AltSchool.
There is also plenty of additional information on the School´s site.