In this first three-part post, John Larmer describes how he and co-author Susie Boss answered the question in their newly published book, 'PBL for 21st Century Success: Teaching Critical Thinking, Collaboration, Communication, and Creativity'. In the next post, Deborah Esparza will review the book from "the field". For the final post, co-author Susie Boss has been invited to explain why she and John choose this topic.