The document discusses the development of the "Four Cs" framework for 21st century skills in K-12 education. It began with 18 identified skills in 2002 but interviews determined the most important were the 4 Cs of critical thinking, communication, collaboration, and creativity. The challenge now is incorporating these skills into classroom practice. The rest of the document provides guidance for teachers on developing lessons that focus on the 4 Cs through strategies like letting students lead their learning, encouraging inquiry and collaboration, and fostering critical thinking and creativity.