The warm-up prompt for this lesson asks students to review the properties of reflections, which we studied in the last lesson. The warm-up follows our Team Warm-up routine. I choose students at random to write the team's answer on the board.
Following the warm-up, I display the agenda and learning targets for the lesson. To activate prior knowledge, I ask the class to help me name three different ways to move an object without changing its size and shape. I tell class that today we will focus on the properties of translations.
During this part of the lesson, students use construction tools to create the image of a triangle under translation. The goal of this hands-on activity is to help students to focus on the properties of translations.
I often let students choose their partners within their cooperative learning teams for paired activities, but for this activity I direct them to work with their shoulder partners. I want a more-capable student in each pair, because they will need to follow directions carefully. Then, I distribute the handout for the activity, 2 copies for every team of 3-4 students.
I give instructions with the help of the slide for the activity. Students will need a straight-edge, compass, and protractor. I ask students to get out their notes on constructing parallels from the previous lessons. I ask them to place their desks in pinwheels. They will be working in pairs, so that they can help each other with the constructions. I ask students to use the Rally Coach routine.
As students get started on the activity, I circulate around the classroom offering help where needed. I am on the lookout for:
If many students are struggling to understand the directions, I call the class's attention to the front board, where I can demonstrate the first steps of the construction using the document camera.
Once students have completed the construction, I ask them how they expect the sides and angles of the reflected image to compare to the sides and angles of the original. I ask them to use their compass and a protractor to verify that corresponding sides and angles of the image and pre-image are have equal measures.
In this section, we use Guided Notes to summarize the properties of translations.
I begin by displaying a model sample of student work from the Constructing a Translation activity on the front board using a document camera and asking the class to help me summarize its properties.
For homework, I assign problems #32-34 of Homework Set 2. Problem #32 gives students an opportunity to review the properties of translations. I encourage them to look for the answers in their notes. Problem #33 asks students to visualize and draw the image of a polygon under translation along a vector. Problem #34 gives students the opportunity to apply the properties of rigid motions to solve a real world problem.