Xfce - Xfce is a lightweight desktop environment for UNIX-like operating systems. It aims to be fast and low on system resources, while still being visually appealing and user friendly.
PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
Budgie Desktop - Budgie Desktop is a familiar, modern desktop environment. - GitHub - BuddiesOfBudgie/budgie-desktop: Budgie Desktop is a familiar, modern desktop environment.
Clever - syncing between education applications for K-12 schools
LXDE - Why will you like it? Less resource needs. You can use it on your less-pricey embedded board or salvaged computer. Component-based design. Don't want something in LXDE, or you don't want to use LXDE but only part of it?
Claroline - Claroline is a collaborative eLearning and eWorking platform.