PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
Meazure - What are the dimensions of that image? How big is this window?
Clever - syncing between education applications for K-12 schools
ScreenRuler - ScreenRuler lets you measure objects on your Ubuntu desktop using six different metrics.
Claroline - Claroline is a collaborative eLearning and eWorking platform.
Bluegrams Screen Ruler - A lightweight and configurable ruler tool for Windows Desktop.