Students will learn how to use the vertical line test to determine whether a relation is a function. They will also learn how to use the horizontal line test to determine whether the inverse of a relation is a function. Here's a good demonstration. After that, students will learn how to identify functions and non-functions from ordered pairs and tables. Finally students will learn how to algebraically manipulate an equation to determine whether it represents a function or not.

Conclude by giving your students these challenges:

- Factoring Puzzle
- Where Is the Dot? by NRICH
- Arclets by NRICH
- Multiplication Square by NRICH
- 2015 AMC 8, Problem 11