Requirements and what each one depends on

The map

Rows are the threads of the curriculum. Columns are the year the idea becomes a requirement. A box holds one or more official skills. Click it. The panel names what it requires, why, and what it unlocks. A green tint means a student page teaches this concept; if the concept continues in a later year, that later skill is not in the page. For one circle per official skill, use the skill graph.