draw.io

draw.io is the most tightly Google Drive integrated diagramming application available.It offers different tools to create graphics. draw.io is completely free online diagram editor built around Google Drive(TM), that enables you to create flowcharts, UML, entity relation, network diagrams, mockups and more. Teachers can use this application to make mental maps, graphic organizers, or others. Also, students can make a review of different topics through a mental map in this application.