Are sequences functions? Why can't the popular "vertical line test" be applied in some cases to determine if a relation is a function? How does the idea of rate of change connect with simpler ideas about proportionality as well as more advanced topics in calculus?

How much do you know...and how much do you need to know?

Helping your high school students develop a robust understanding of functions requires that you understand mathematics deeply. But what does that mean?

This book focuses on essential knowledge for teachers about functions. It is organised around five big...