Unit 1, Lesson 1
Moving in the Plane
Grade 8
Preparation
Lesson Narrative
The purpose of this lesson is to introduce students to translations and rotations of plane figures and to have them describe these movements in everyday language. Expect students to use words like “slide” and “turn.” In the next lesson, they will be introduced to the mathematical terms. The term “transformation” is not yet used and will be introduced later in a later lesson.
In all of the lessons in this unit, students should have access to their geometry toolkits, which should contain tracing paper, graph paper, colored pencils, scissors, ruler, protractor, and an index card. For this unit, access to tracing paper and a straight edge are particularly important. Students may not need all (or even any) of these tools to solve a particular problem. However, to make strategic choices about when to use which tools (MP5), students need to have opportunities to make those choices. Apps and simulations should supplement rather than replace physical tools.
This is the first exercise that focuses on the work of building a mathematical community. Students have the opportunity to think about what a mathematical community is and to share their initial thoughts about what it looks like and sounds like to do math together in a community.
- Describe (orally and in writing) a rotation of a shape using informal language, e.g., “turn left,” ”quarter turn,” etc.
- Describe (orally and in writing) a translation of a shape using informal language, e.g., “slide,” “move,” “shift,” etc.
Let’s describe ways figures can move in the plane.
Required Preparation
Assemble geometry toolkits. It would be best if students had access to these toolkits at all times throughout the unit. Toolkits include tracing paper, graph paper, colored pencils, scissors, ruler, protractor, and an index card to use as a straightedge or to mark right angles. Access to tracing paper is particularly important in this unit. Tracing paper cut to a small-ish size (roughly 5 in by 5 in) is best—commercially available “patty paper” is ideal for this. If using larger sheets of tracing paper, such as 8.5 in by 11 in, cut each sheet into fourths.
Make a space for students to place their sticky notes at the end of the Warm-up. For example, hang a sheet of chart paper on a wall near the door.
A vertex is a point where 2 or more edges meet. When there is more than 1 vertex, they are called vertices.
The vertices of this polygon are labeled , , , , and .