Skolelinux, alias Debian Edu, is a modified Debian distribution that was specifically developed for use in schools. The project has its roots in Norway. The included configurational profiles make it easy to install servers with an LDAP user database, a terminal server, or workstations and laptops. The software is based exclusively on free software and provides a range of learning programs. Skolelinux is considered a reliable, stable, and easy-to-administer distribution. As the distribution allows old PCs to be used as thin clients, the use of Skolelinux also contributes to the protection of the environment.
You can find more information on the project page.