Reflections

Reflections

Reflecting

Opening

Reflecting

Read and Discuss

  • You can reflect a figure across a line to get a mirror image of the figure.
  • Every point is the same distance from the line of reflection, and the reflection, or mirror image, is the same size as the original image.

Reflect Points

Opening

Reflect Points

You can reflect a point across the x-axis or y-axis on the coordinate plane. In this case, the point (−3,2) has been reflected across each axis.

  • What are the coordinates of the reflection of (−3,2) across the x-axis? The y-axis?

Reflect Figures

Opening

Reflect Figures

Look for a pattern, or structure, as you reflect the figure in the Coordinate Point Plotter interactive.

  • Locate the vertices of the mirror image, or reflection, of the figure.
    • Use the x- or y-axis as the mirror.
    • Reflect the figure across the x- or y-axis.

INTERACTIVE: Coordinate Point Plotter

 

Math Mission

Opening

Find a pattern for naming the vertices of a figure reflected across one of the axes on the coordinate plane.

Locate the Vertices

Work Time

Locate the Vertices

  • Locate the vertices of each figure reflected across the x- or y-axis.

Use the Coordinate Plane Plotter interactive if you find it to be helpful.

HANDOUT: Locate the Vertices

INTERACTIVE: Coordinate Plane Plotter

Start with one vertex and find its reflection.

Prepare a Presentation

Work Time

Prepare a Presentation

Describe the process you used to find each reflected vertex.
 

Challenge Problem

  • Choose a line of reflection that is not the x- or y-axis.
  • Reflect the figure across the line on the coordinate plane.

Use the Coordinate Plane Plotter if you find it to be helpful.

HANDOUT: New Reflections

INTERACTIVE: Coordinate Plane Plotter

Make Connections

Performance Task

Ways of Thinking: Make Connections

Take notes about the strategies you can use to reflect figures on a coordinate plane.

 

As students present, ask questions such as:

  • What strategy did you use to reflect the figure?
  • How is your strategy different from the other methods mentioned so far? How is it similar?
  • How do you know that each point is reflected correctly?
  • What did you notice about the coordinates of the reflected figure’s vertices?

Describe Reflections

Formative Assessment

Summary of the Math: Describe Reflections

Write a summary describing how to reflect images on a coordinate plane.

Check your summary.

  • Do you include what you observed about the coordinates of the reflected points?

Check Your Understanding

Formative Assessment

Check Your Understanding

Work on this Self Check by yourself.

  1. Create a figure or design on the coordinate plane that satisfies the following criteria:
    • At least one vertex has coordinates that include a number and its opposite.
    • At least one vertex has coordinates that are both non-integers.
    • At least one vertex is in each quadrant.
    • At least two vertices have x-coordinates that have equal absolute values.
    • At least two vertices have y-coordinates that have equal absolute values.
  2. Label each vertex with its ordered pair, and explain how your figure or design meets the criteria.

Use the Coordinate Plane Plotter interactive if you find it to be helpful, but record your work on the handout.

HANDOUT: Check Your Understanding

INTERACTIVE: Coordinate Plane Plotter

Reflect On Your Work

Work Time

Reflection

Write a reflection about the ideas discussed in class today. Use the sentence starter if you find it to be helpful.

A strategy that I found useful in reflecting a figure on the coordinate plane is …