I find this approach works well because you don't have to ask "why did he make that design decision" but instead I intentionally make common mistakes a beginner would make, wait until they become an issue, and then I demonstrate how we can fix that issue. As a result you really get to understand not only how to create a web app in Go but also why developers tend to follow different design patterns.
I said this in another comment, but it is based on Michael Hartl's Rails Tutorial. I think showing someone how to go from nothing to a full app is a great way to help them get into web development without the frustration that comes from piecing together blog posts/docs/trial&error.
If you are interested in Go I'd love to get your feedback :) and if it isn't obvious, I am the author of the book.