These are the finished examples from lessons 2, 3, and 4. They are the same as the ones in the videos, except for a couple of differences:
This expands the selection-dependent inputs example from earlier, and shows three different ways to do the same thing: the lazy way, which shows and hides chunks of HTML, and two better ways, which use JSON to store and retrieve the data that is used to assemble a drop-down list on the fly.
This is the selection-dependent inputs example again, but now it uses radio buttons instead of a drop-down list, and the form for the selected option appears right below it. It animates showing and hiding the forms so that it is not jarring or disorienting.