Level O expands on precalculus concepts from Level N to focus on high-level mathematical analysis. Differential Calculus

Mastering higher-order derivatives and their applications.

Here is the hard truth. The search for the is a symptom of a larger problem: The Kumon "self-learning" model breaks down at calculus.

For a student reaching Level O, the familiar comfort of numbers has long vanished. The solution book doesn’t deal in arithmetic; it deals in the behavior of functions

: First-order differential equations and their particular solutions.