The well-renowned Physics Classroom website (see the 11-12-2004 Scout Report) recently introduced Concept Builders, a series of interactive tutorials designed to help students understand and apply physics concepts. As of this write-up, the collection features thirteen concept builders, which address topics including Newton's Law of Motion, circular motion and gravitation, electric circuits, and waves and colors. When visitors select one of these concept builders, they will view a series of short tutorials related to the concept. Each tutorial is accompanied by a learning goal, which allows learners and instructors to locate relevant tutorials with ease. To participate in each tutorial, visitors simply need to select "Launch Concept Builder." Next, visitors are prompted to select a level ("apprentice," "master," or "wizard"). Based on their selection, visitors will view six practice problems related to the tutorial's learning goal. Each of these interactive tutorials is accompanied by a helpful set of teacher's notes and suggestions for instructors interested in incorporating Concept Builders into their curriculum.