# Lesson 12

Changing the Equation

These materials, when encountered before Algebra 1, Unit 6, Lesson 12 support success in that lesson.

### Lesson Narrative

In this lesson, students prepare for the associated Algebra 1 lesson by focusing on evaluating quadratic expressions correctly, particularly for a negative input (for example, evaluating \(x^2+10\) when \(x\) is -3). Additionally, they recall the effect on a graph of a linear function when its parameters vary. Students will encounter and rehearse some language needed to describe the effect of varying the parameters \(a\) and \(c\) in a function defined by \(ax^2+c\) in the associated Algebra 1 lesson. When students evaluate sample work and explain who they agree with and why, they are critiquing the reasoning of others (MP3). When students vary the parameters in a linear function and record their observations, they have an opportunity to attend to precision through their word choices (MP6).

### Learning Goals

Teacher Facing

- Evaluate quadratic expressions for negative values of the variable.
- Revisit the effect on its graph of changing the parameters in a linear function.

### Student Facing

- Let's look at quadratics with negative inputs.