Teachers often notice that even well-prepared lessons can overwhelm students — too many steps, too much new information, and attention that fades quickly. Why does this happen, and how can instruction be designed to support rather than overload learners? In Cognitive Load Theory  (Sweller, Ayres, & Kalyuga, 2011), the authors explain how the limits of working memory shape how people learn, and how teachers can use this knowledge to design more effective instruction. The theor