BookWidgets - BookWidgets is an excellent application that let you create engaging exercises in minutes and easily share a varied variety of beautiful and fun activities with your classroom and others.
Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.
Padlet - Visual boards for organizing anything.
Eduflow - Digital learning that actually teaches students something
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
Kialo - Kialo is the platform for rational debate. Empowering reason through friendly and open discussions.