In this lesson, students use the vertex form to determine the maximum or minimum value of a function and to solve problems.

An increased emphasis on using the structure of the vertex form to explain maximums and minimums also distinguishes the work in this lesson from earlier work. Previously, students may have relied on their observation of graphs, recalling that the graph of an equation opens upward when is positive and downward when is negative. Here, they justify the classification as a maximum or a minimum using reasoning about the positivity of squared expressions. 

As students reason about and explain why a vertex is a maximum or a minimum, they practice constructing logical arguments (MP3). They also rely on the structure of the quadratic expressions to find the vertex and classify whether it is a maximum or a minimum (MP7).