Ask your transcript what you know and it answers with five letters. Ask Sapling and it answers with a map: every concept in your course as a node, every relationship as an edge, and a mastery score on each node that moves as you study. This is how that map actually gets built.
Nodes come from your materials
When you upload a syllabus, slides, or notes, Sapling reads them and extracts the concepts your professor actually teaches — not a generic textbook ontology. A data structures course yields nodes like binary search trees, rotations, hashing, dynamic programming; each node keeps pointers back to the documents it came from. That grounding is why the tutor can cite the exact slide behind an answer.
Edges come from structure — and from you
Some edges are in the material itself: rotations rest on binary search trees, memoization rests on recursion. Others are drawn from behavior — when a quiz question exercises two concepts, when a note links ideas, when the tutor walks you from one topic into its neighbor. The graph you end the semester with is partly the course’s anatomy and partly a record of how you moved through it.
The edges we care about most cross unit boundaries. Courses are taught in chapters, but understanding is not chaptered — the moment hashing connects to complexity analysis in your head is a genuine event in your learning, and it deserves to be a genuine edge in your map. Those cross-unit links are the difference between a table of contents and a mental model.
Mastery is the color
Every node carries a mastery score from 0 to 100, rendered as a tier: mastered, learning, struggling, unexplored. The score moves on evidence — a quiz answer, a flashcard rating, a TeachBack explanation — and every change is kept as an append-only event, so your history is a trail, not a single overwritten number. Mastery can go down. Discovering a gap is information, and the map should say so.
What the graph drives
- Quiz targeting: questions aim at the concepts where mastery is low or stale, and every answer writes a delta back to the node it tested.
- Review scheduling: spaced repetition draws cards from the lowest-mastery concepts first, walking edges to catch the upstream ideas a weak node depends on.
- Tutoring: a session on one concept pulls its neighbors into context, so explanations meet you where your actual gaps are.
- Study guides: pick an exam, and the guide assembles from your own library, weighted toward your weakest reachable nodes.
One map, read and written by everything. That is the whole architecture, and it is the reason a semester of studying in Sapling leaves you with something your transcript never captures: not a grade, but the shape of what you know — including the honest holes in it.