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The UI is focussed on making the website more visual. The focus of the design lies in the visual representation of the courses. The eye is directly brought to the images of the courses and the course ratings. Then when they hover over a course with their mouse, it will cycle through images in the courses and people can get a nice feel for the course. This interface is very intuitive and learnable, and also efficient for getting a quick over-view of courses. Then, if you want to go into more depth you can use the search and browse features which take you dynamically to another page. There is a hit to learnability since the UI is in a somewhat non-standard configuration
2 - Video Intro
The UI is meant for when the site is new, and people don't know quite what to expect yet. There is a video introduction about what rethinkED is about, then directly under the video users can browse courses. This layout is easily learned since it follows all common conventions of playing videos and using web UI widgets. It's also efficient in conveying what someone would want to do what when first visiting a site such as this.
3 - MobileDetailed
This UI is designed for small screens (mobile phones). The UI takes advantage of the smartphone’s touch interface for easy navigation through the app, and presents the reviews in an efficient manner, again with the option of advanced search criteriasomewhat more complicated than the first two but more can be accomplished. This configuration would be more useful for someone who knew what they wanted, this layout would allow them to get their faster than the first two, and so there is an rise in efficiency for these types of users. The learnability however is not affected, since it uses similar UI components that are standard across websites today.