Shapes On A Plane- Day 4

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SWBAT describe the effect of dilations, translations, rotations, and reflections on two-dimensional figures using coordinates.

Big Idea

Students use ordered pairs and algebraic rules to plot similar figures on a coordinate plane.

Warm Up

7 minutes

For today's Warm Up, I'm giving the students an assignment that builds on the previous days' lessons while extending their understanding. I give them a shape in quadrant II and instruct the to translate the shape so that it ends up in quadrant IV. This open-ended task will allow important class discussions about which transformations move figures from quadrant to quadrant and how the resulting coordinates are changed from the original figure provided. This also helps to reinforce the students' ability to verify experimentally the properties of reflections and translations.

Learning Objective & Key Vocabulary

2 minutes

Once students have shared their ideas during Warm Up, I share the day's Learning objective and key vocabulary. I want to give specific focus to the word "dilation" since it is likely unfamiliar to students and they will have the opportunity to use it in context during today's lesson.

Work Time

30 minutes

For today's Work Time, I will be using one of my favorite lessons borrowed from "The Missing Link" Workshop series, which was originally funded by the Annenburg Foundation in the early 1990's. Today's lesson is from Workshop 1, Lesson 2, and I have renamed it "Flip Family" for my students.

During the lesson, the students plot points provided to reveal a figure. They then apply an algebraic rule to determine the coordinates of another Flip figure that has been transformed in some way. This allows them to develop an understanding of the concepts of congruence and similarity using transformations, namely dilation. 

Due to time constraints, I ask students to plot "Zip" Flip. I then have students number 1 to 5 and plot the corresponding character (1- Zap, 2- Pip, 3- Pop, 4- Bip, and 5- Bop). I provide plenty of extra copies of the first quadrant grid for any student who wishes to plot more than the two assigned figures.

To facilitate student understanding of the task, I share The Flip Family coordinate page and model the application of the algebraic rule for the first few points of each character. For example, "Zap" has the coordinate rule (2x, 2y), meaning students must multiply both the x- and y-coordinate values from Zip Flip by 2. I then ask students to look at each of the rules and predict which characters will be family members and which will be impostors by circling the names of the family members on their worksheets.

I then start the timer for the 25-minute work session. 

For students who finish plotting before the Work Time timer sounds, I ask them to transfer their work onto a transparency that I can then share with the class on the document camera. These will be used the following day to launch class discussion.


In Your Journal

6 minutes

Once the Work Time timer sounds after 25 minutes, I ask students to respond to three journal prompts in their journals

  1. Which characters were members of the Flip family?
  2. Which characters were impostors?
  3. Is there a way to know without graphing the coordinates?

I explain that we will share the responses to these questions during the next day's lesson Warm Up. Once students have finished answering, I direct to close their journals so I know they are ready to be dismissed.