A learning platform is designed for its students' connection. Ours targets the country's median connection: mobile, intermittent, billed by volume. Everything that enters the campus is reworked until it fits that constraint.
In practice: text and exercises take precedence over video, videos exist in low definition, pages remain readable once loaded, and work in progress is kept on the device so it survives a network drop.
The constraint disciplines instructional design. A lesson that holds without forty minutes of video is a lesson whose structure has been thought through, and it is faster to revise at exam time.
The same choice governs the whole public site: every page is served in a few dozen kilobytes, and reads on an entry-level phone as well as on a desktop computer.