Though it’s now been 5 years, this remains our best (and fastest read) book on the four key skills of critical thinking, communication, collaboration, and creativity.
Budhai, S & Taddei, L. (2015). Teaching the 4Cs with technology: How do I use 21st century tools to teach 21st century skills? ASCD Arias. http://www.ascd.org/Publications/Books/Overview/Teaching-the-4Cs-with-Technology.aspx