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 o

Why does it matter whether we state definitions carefully when we all know what particular geometric figures look like? What does it mean to say that a reflecti

"A series for teaching mathematics."--P. [1] of cover.

Do your students think that the vertical line test is indispensable and foolproof for determining whether a relationship is a function? Do they believe that eve

Focuses on essential knowledge for teachers about proof and the process of proving. It is organised around five big ideas, supported by multiple smaller, interc