Justin Reich teaches this session of MIT's CMS.595 Learning, Media, and Technology, covering cognitive load theory and its implications for instructional design. He walks through the mechanics of working memory and short-term memory, explaining why limited processing capacity creates bottlenecks when people try to learn new material, especially material delivered through technology. The lecture connects these cognitive constraints to practical questions about how educational tools should be designed so they do not overwhelm learners. Students contribute their own prior experiences with education technology, testing the theory against real classroom and online learning situations they have encountered. Reich uses the discussion to surface where common ed-tech design choices help or hinder learning given what is known about memory limits. Fifty-six minutes of lecture and discussion aimed at future designers and researchers of learning technology.