Common topic titles

"Intro"s and "Intro to"s

An "Intro" is the introduction associated with formulas and theorems. An "Intro to" is any introduction not associated with a formula or theorem. "Intro to"s have specific titles, such as "Intro to complex numbers."

Challenge

A challenge is a difficult problem, intended to teach perserverance. Challenges shall be distributed evenly throughout all K-12 courses.