# Lesson 23

Comparing Functions

These materials, when encountered before Algebra 1, Unit 7, Lesson 23 support success in that lesson.

### Lesson Narrative

In this lesson, students evaluate functions at different values to compare them and rewrite quadratic functions into vertex form to find the vertex. In the associated Algebra 1 lesson, students use the vertex form of quadratic functions to find the vertex and solve problems using the maximum and minimum. The work of this lesson supports students by improving their fluency with evaluating functions and changing the form of an equation into a more useful one. Students look for and make use of structure (MP7) when they use an equation in standard or factored form to identify the vertex of a graph.

### Learning Goals

Teacher Facing

- Determine which $x$-value has a greater $y$-coordinate for a given function.
- Write quadratic equations in vertex form and find the vertex.

### Student Facing

- Let’s evaluate and compare functions.

### CCSS Standards

Building Towards