When the World Wide Web was first created, the first web pages tended to be static things formatted to mimic printed documents. (first web page is here).
Many other media migrating to the web has followed this same trend. Music is still created in albums largely but it is not purchased that way online; most songs are purchased as individual tracks.
The World Wide Web took about 5-10 years to start messing with dynamic content and non static pages. The same thing is happening to eBooks too, specifically eTextbooks. The first eTextbooks were largely just digital copies of the print versions. This was logical but time has moved on. McGraw-Hill has announced at CES (H/T Engadget) this week a new type of eTextbook which is adaptive. As you read the textbook, it asks you questions on your comprehension. If you get some wrong, the upcoming text will change in order to add follow up content based on what you got wrong. This is a great idea and is a logical next step in online learning.
There are two challenges I can see.
First, the company will have to create more content. Each topic will have to be in more depth so extra stuff can be presented.
Second, it means not everyone will have the same experience. Can a teacher tell a class to “turn to page 266″? Probably but this type of learning is geared to self directed learning more than teacher directed learning. This will be awesome in a blended learning type of scenario I imagine. Students can read the material the night before, then the teacher will explore the topics the next day. Not only that, but the teacher should be able to see what areas of content the class had trouble with and adjust the lesson to cover those topics.
This is a disaggregation of the way classrooms work now into how they will work in the future.