# Lesson 15

Preparing for Vertex Form

These materials, when encountered before Algebra 1, Unit 6, Lesson 15 support success in that lesson.

### Lesson Narrative

In this lesson, students have an opportunity to use a graphing calculator to do the same things they will in the associated Algebra 1 lesson. In the warm-up, students use intercepts and other features of graphs to compare and contrast them, drawing on relevant vocabulary. Then, they change the parameters of a linear function and draw connections to the features of a graph representing the function. (In the Algebra 1 lesson, they do a similar activity involving quadratic functions.) Then, they practice identifying equivalent expressions. This is in preparation for the associated Algebra 1 lesson, when they will need to rewrite expressions in equivalent forms, including expanding expressions like \((x-5)^2\). Students notice and make use of structure (MP7) both when they notice how changing a parameter in a function affects its graph and when they use structure to identify equivalent expressions.

### Learning Goals

Teacher Facing

- Experiment with changing the parameters in a linear function and noticing the effect on the intercepts of its graph.
- Practice identifying equivalent expressions.

### Student Facing

- Let’s notice how the numbers in a function affect its graph.