NWEA Assessments - NWEA Assessments creates a personalized assessment experience by adapting to each student's learning level.
TisaneAPI - Detect hate speech, cyberbullying, and more in 27 languages
ALEKS - ALEKS is a web-based artificially intelligent assessment and learning system that uses adaptive questioning to accurately determine exactly student knows.
YouTube Kids - YouTube for the youngins on iOS and Android
iSpring QuizMaker - iSpring Quiz Maker is easy-to-use quiz software. Create interactive quizzes and surveys in HTML5 & Flash and embed them in a website or publish for any LMS!
Interland by Google - A game to help kids be safe, confident explorers online