Lesson 8
Equations and Graphs
Lesson Narrative
In this lesson, students write an equation for a parabola and rewrite it in vertex form. Then, they match graphs of parabolas to equations. Students reason abstractly and quantitatively (MP2) as they create a parabola equation by applying the concept of distance calculations.
Learning Goals
Teacher Facing
 Generalize (using words and other representations) the process of repeated distance calculations to derive an equation for a parabola in the coordinate plane.
Student Facing
 Let’s write an equation for a parabola.
Required Materials
Required Preparation
The graphing technology is for use in the extension problem of the activity Card Sort: Parabolas.
Learning Targets
Student Facing
 I can derive an equation for a parabola in the coordinate plane given a focus and a directrix.
CCSS Standards
Addressing
Glossary Entries

directrix
The line that, together with a point called the focus, defines a parabola, which is the set of points equidistant from the focus and directrix.

focus
The point that, together with a line called the directrix, defines a parabola, which is the set of points equidistant from the focus and directrix.

parabola
A parabola is the set of points that are equidistant from a given point, called the focus, and a given line, called the directrix.