XYZ online textbook platform

What

Anyone who has been stuck on a math problem at midnight knows the answer key doesn't help. Seeing the answer isn't the same as seeing how. What you actually want is someone sitting next to you, working the problem through, at your pace, as many times as it takes.

That is what XYZ Textbooks built. It's an interactive textbook where every math problem comes with three or four video tutorials of a real instructor teaching you how to solve it. You pick the instructor whose explanation clicks for you, and you watch as much as you need: one step, the whole solution, or the same problem again from a different teacher.

It sounds simple for a student. It isn't simple to run. Hundreds of problems per book, times three or four videos each, across a catalog of more than 25 titles, adds up to terabytes of video that have to be stored, maintained and streamed on demand, the moment a student taps a problem.

How

Architecting for the video, together. I worked alongside our lead engineer to architect the system that makes this possible: how tens of thousands of videos are organized, tied to the exact problem they teach, kept current as titles are revised, and delivered fast enough that a student never waits to get unstuck.

Leading the UI. When it came to building the experience students actually touch, that was mine to lead. The reader had to feel like a book, not a video portal: real chapters and page navigation, math that renders cleanly and stays legible at any zoom, and video sitting right at the problem where it helps rather than hidden in a separate "resources" tab. The hard part was choice without clutter. Three or four instructors per problem, across hundreds of problems, is a lot of video to put one tap away without burying the math itself.

Designing the payment portal. On top of the reader, I designed the entire payment portal: the purchase flow, the cart, and the account that connects a purchase to a student's bookshelf. Owning checkout meant XYZ set its own prices instead of accepting a courseware vendor's terms, and that still shows today: the Applied Calculus eBook sells for $45, in a market where a textbook plus a mandatory access code routinely clears $200.

Outcomes

• 13 years later, it's the same. The UI I led is still the one students use on xyztextbooks.com today. For a web application built in 2013, that's the outcome that matters: it outlasted every framework trend that came after it.
• A teacher for every problem. Students get a choice of real instructors on every problem in the book, not a single answer key, and they can watch as much as they need.
• Built to carry the weight. A catalog of 25+ titles, with terabytes of video behind it, still served on demand from the architecture we designed.
• One product, end to end. The reader, the video tutorials and the payment portal ship as one experience, with one account and one login.