Our lecture videos this module begin with the major innovation of the graphical interface: enabling people to perform input directly on top of output. This directness makes interfaces easier to learn because it enables people to recognize familiar elements. And continuous feedback makes interfaces easier to use, encourages exploration, and prevents errors. To illustrate the benefits of direct manipulation in real interfaces, the videos provide several examples of both particular designs and interface styles. I find that's a lot more useful than just stating abstract principles. Now is a good time to remind everyone that I am not endorsing (or rejecting) any particular product, organization, or person. What I am doing: real people in the real world make real design decisions -- you can learn from this -- and in this course I'll discuss these concrete examples so you can gain real knowledge. The rest of the videos will cover topics related to the importance of representations, such as understanding a user's mental model and helping people to distribute cognition. I will show some examples of how representational differences can impact performance. As you watch these videos, think about how you have arranged or lamented representations in your everyday life. Maybe you put your keys by the door, sunglasses on your hat, or a post-it on your laptop? You'll get a chance to delve into these examples in the assignment.