Doug Callahan
7th grade
Glen C. Jones Middle School
Gwinnett County Schools

Contents

Task GPS Addressed Video Classroom Materials

Task

Overview In this task, students will use construction techniques to create a regular octagon. Illustrative Task You’ve already completed many challenging constructions, so you are ready for a final challenge: The Construction of a Regular Octagon. How would you construct a regular octagon? Discuss this with a partner and come up with a strategy. Think about what constructions might be needed and how they might be completed. Be prepared to share your ideas with the class. Experiment to see if your strategy works and justify why your strategy works.

GPS Addressed

M7G1. Students will construct plane figures that meet given conditions. Perform basic constructions using both compass and straight edge, and appropriate technology. Constructions should include copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line. Recognize that many constructions are based on the creation of congruent triangles.

Video Information

Use these questions to guide your thinking about some of the important teacher ideas in the lesson featured in the video clip. What kinds of questions does the teacher ask to promote students’ problem solving? How is the teacher gauging students’ current understandings and building from those understandings? Consider the GPS standards listed with this video. What makes this lesson different from lessons you have taught on this topic?

Classroom Materials

Lesson Plan