Khan Academy
Khan Academy: Algebra Ii: Functions: Model With Composite Functions
Given two basic functions that model a real-world situation, compose them in order to model a more complex situation. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Teaching Composition of Functions
Dr. Math gives several suggestions for teachers when helping students understand the concept of composition of functions.
Math Medics
S.o.s. Math: The Chain Rule
Finding derivatives by using the chain rule is explained through examples in this tutorial.