CK-12 Free Online Textbooks, FlashCards, Exercises, RWA's, Simulations - keep learning this summer | Information Technology Learn IT - Teach IT | Scoop.it
CK-12 Foundation provides a library of free online textbooks, videos, exercises, flashcards, and real world applications for over 5000 concepts from arithmetic to history

Via Tom D'Amico (@TDOttawa)