Wednesday, February 22, 2012

Today's topic? Topics!

< reorganization >

Last week we at Khan Academy revealed the first pieces of a long-term project to reorganize the content on the homepage and throughout the site. You may have noticed the removal of a number of playlists, notably "Developmental Math" and "Pre-Algebra", and the appearance of newly organized topics called "Algebra" and "Arithmetic and Pre-Algebra". We have grouped the videos under each topic into subtopics as well, to better expose how the thematic building blocks come together and the logical ordering between them. We think showing the structure and consolidating related subtopics under one supertopic is a big improvement over the somewhat haphazard collection of playlists that had evolved over time. Here is what one of the new topics looks like:

The shift in terminology from "playlist" to "topic" is significant: Playlists are completely linear and imply a passive mode of consumption. The concept of a playlist does not include exercises (although the videos in the playlist do have related exercises) and so the natural flow of watching a playlist precludes stopping to do an exercise to practice the knowledge that you've just absorbed.

< topics >

So what is a topic? A topic can represent a single concept or related group of concepts, and unlike playlists they are arranged in a tree. So "Math" is a top-level concept, with "Algebra" beneath it and "Solving linear equations" beneath that. Within these lowest-level topics is our content: Not just videos, but eventually exercises and any other tools that we come up with to teach that topic. The ordering is meaningful so a student can look at the content in a topic and see what relevant videos and exercises teach this concept and the logical order to complete them.

This has both immediate and long-term effects on how students find and use our content. In the short term, we hope that specific and relevant content will be easier to find on the homepage, and there should be less confusion about what concepts that student is actually learning in each topic. In the longer term, we want to encourage a more active and nonlinear mode of participation: students will have the option to interleave videos and exercises for a more active learning session, and students will be able to tackle specific topics by setting goals and getting feedback on a more granular level how they're progressing. This will also help us clean up the Knowledge Map so it's easier to read and navigate.

< api >

One important note for users of the public API: If you have been using to get a list of playlists for displaying our videos in your application, you will want to migrate to the new topic tree API: The playlists are becoming less coherent as we reorganize content and will eventually be deprecated in favor of the new organization, and all the new features in the API will be referencing topics. We look forward to seeing what navigation methods you find effective for the topic tree.

< ta-da! >

We are really proud of this architectural and pedagogical improvement. We hope to have all the topics under Math organized in the next few months, and to start rolling out exciting new features that leverage this infrastructure soon. Watch this space, and please leave your feedback in the comments!

< / tom >


  1. Very exciting. I look forward to seeing how this new structure plays out in the rest of the website. Are you planning on reorganizing the exercises in the same way and is there / will there be an API page that keeps an updated list of exercises as well?

    1. Yes, the exercises will be organized in the same way as the videos into the topics. In fact, there are already some exercises being listed on the topic tree API page in their relevant topics, however we are not displaying them on the homepage as yet.

    2. Can I help organize the videos and exercises into the new thematic building blocks and topics / subtopics?

  2. Interesting fix. I've noticed that some videos are integrated within the framework. For example, the Art History videos link to a different webpage and no analytics are possible by watching these videos. And the Art of the Problem videos by Brit Cruise are also unavailable via the KA main page. I have to subscribe to the channel via youtube. Is there a plan to integrate these materials as Sal's videos are?

  3. Looking forward to the Map cleanup.

    Also, I posted this as a suggestion, but I'll mention it here too: I liked it better when I could see all of the problem sets I had unlocked, rather than just the next five. I can see the point to keeping the list on the left short and to the point, but I'd really like a way to see everything I can do, too.

    Anyway, thanks, loving KA lots!

  4. Two things: Any update on the iPad app? and could you make a way to print off the Knowledge Map? I know it is forever being updated, but it would be handy for teachers to be able to look at it.

    Keep up the great work!

  5. Interesting. I am using the API for a windows phone app I have been working on and this topic structure completely makes sense. I am actually already using this tree structure using the api/v1/playlists/library feed which is organized in a tree but not as clean as this new topic feed.

    Is there a place I can get updates on all the enhancements you guys are making in the apis?

    You can take a peek at the app I have in beta here if you like:

    Keep up the great work. Thanks.