# Lesson 18

Practicing Point by Point Transformations

### Lesson Narrative

This lesson is optional.

This lesson gives students more practice defining sequences of transformations in terms of labeled points on the figure. It will be especially helpful if students had difficulty with the previous lesson. The first obstacle course activity includes a grid to provide some scaffolding yet still encourages students to think about the transformations in terms of the labeled points. For the second activity the grid is removed again entirely in preparation for subsequent lessons.

The goal is for students to start to develop a systematic, point-by-point sequence of transformations that will work to take any pair of congruent polygons onto one another. This is especially important because when transformations are used in triangle congruence proofs in a subsequent lesson, students will be justifying how they know that a certain transformation will take one triangle onto another.

Students practice attending to precision (MP6) when they describe transformations step by step.

Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available.

### Learning Goals

Teacher Facing

• Draw the result of a transformation (in written language) of a given figure.
• Explain (orally and in writing) a sequence of transformations to take a given figure onto another.

### Student Facing

Let's figure out some transformations.

### Student Facing

• Given a figure and the description of a transformation, I can draw the figure's image after the transformation.
• I can describe a transformation that takes given points to another set of points.

Building On