Execute Program’s lessons don’t unlock until you’ve successfully reviewed their prerequisites

Students of Execute Program can’t immediately access all the lessons in a course. Most of a course’s lessons begin “locked.” Those lessons depend on other lessons in the course: the only initially-unlocked lessons are {those with no dependencies in the course}. Lessons only unlock once {all their dependencies have not only been read, but also recently reviewed (via embedded Spaced repetition memory system mechanisms)}.

This allows course designers to write more focused lessons: Execute Program’s lessons assume solid recall of prior material.

Here’s how their UI explains this mechanism:

This approach suggests one instantiation of The mnemonic medium can be adapted to author an experience which unfolds over time: instead of writing a textbook, write a sequence of hyper-focused lessons, and push them to learners over time as they consolidate knowledge. But: Efficient review scheduling is in tension with gated course sequences

Q. Why do Execute Program’s lessons remain locked until students have completed their prerequisites?
A. So that lessons can be written in a hyper-focused way, including no reminders of those prerequisites.