Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
TaskPaper - Plain text to-do lists for Mac
Clever - syncing between education applications for K-12 schools
Microsoft To-Do - Task management tool
Claroline - Claroline is a collaborative eLearning and eWorking platform.