Chapters in courses

A course was a flat list of lessons. That works for six lessons and stops working at twenty, where the list is really three sections and the only thing saying so is the naming convention someone adopted in the titles. Learners had no sense of where they were in the arc, and authors had no way to move a group of lessons at once.

Courses now have chapters. The course editor has a sidebar that mirrors what a learner sees, and lessons sit inside chapters within it. Drag a chapter to reorder it, drag lessons between chapters, and act on a lesson from the chapter it belongs to rather than from a separate screen. The learner view renders the same structure, so the outline you build is the outline they navigate.

Chapters are optional. A course with none behaves exactly as it did, which matters because most existing courses do not need them and should not have gained an empty layer. The lessons themselves did not change: a chapter is a grouping over what is already there, not a new place to put things.