Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
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.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Padlet - Visual boards for organizing anything.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.
Socrative - Socrative helps teachers engage the class with educational activities to measure and visualize...