ALEX | Alabama Learning Exchange

Grade 7 Mathematics Module 6, Topic B: Constructing Triangles

Classroom Resource Information

Title:

Grade 7 Mathematics Module 6, Topic B: Constructing Triangles

URL:

https://www.engageny.org/resource/grade-7-mathematics-module-6-topic-b-overview

Content Source:

EngageNY

Type:

Lesson/Unit Plan

Overview:

In Module 6, Topic B, students work extensively with a ruler, compass, and protractor to construct geometric shapes, mainly triangles (7.G.A.2). The use of a compass is new (e.g., how to hold it, and how to create equal segment lengths). Students use the tools to build triangles, provided given conditions, such as side length and the measurement of the included angle (MP.5). Students also explore how changes in arrangement and measurement affect a triangle, culminating in a list of conditions that determine a unique triangle. Students understand two new concepts about unique triangles. They learn that under a condition that determines a unique triangle: (1) a triangle can be drawn and (2) any two triangles drawn under the condition will be identical. It is important to note that there is no mention of congruence in the CCSS until Grade 8, after a study of rigid motions. Rather, the focus of Topic B is developing students’ intuitive understanding of the structure of a triangle. This includes students noticing the conditions that determine a unique triangle, more than one triangle, or no triangle (7.G.A.2), and understanding what makes triangles unique requires understanding what makes them identical.

Content Standard(s):

Mathematics
MA2019 (2019)
Grade: 7

18. Construct geometric shapes (freehand, using a ruler and a protractor, and using technology), given a written description or measurement constraints with an emphasis on constructing triangles from three measures of angles or sides, noticing when the conditions determine a unique triangle, more than one triangle, or no triangle.

Unpacked Content

Evidence Of Student Attainment:

Students:

Determine if a unique triangle can be made when given three specific conditions of a triangle.
Explain why three given conditions about a triangle may result in more than one or no triangles.

Teacher Vocabulary:

Construct
protractor
Angle measures
Constraints
Acute triangle right triangle
obtuse triangle
isosceles triangle
Scalene triangle
Equilateral triangle

Knowledge:

Students know:

if three side lengths will create a unique triangle or no triangle.

Skills:

Students are able to:

freehand, draw geometric shapes with given conditions.
Using a ruler and protractor, draw geometric shapes with given conditions.
Using technology, draw geometric shapes with given conditions.
Construct triangles from three measures of angles or sides.
Identify the conditions that determine a unique triangle, more than one triangle, or no triangle.

Understanding:

Students understand that:

from their experiences with constructions, what conditions are necessary to construct a triangle.
only certain combinations of angle and side measures will create triangles.
Constructing a triangle requires a specific relationship between the legs of the triangle and a specific sum between the angles of the triangle.

Diverse Learning Needs:

Essential Skills:

Learning Objectives:
M.7.18.1: Demonstrate how to use a protractor to draw an angle.
M.7.18.2: Construct segments of a given length using a ruler.
M.7.18.3: Recognize attributes of geometric shapes.

Prior Knowledge Skills:

Model using a protractor to draw angles.
Measure the length of an object by selecting and using appropriate tools such as a ruler.
Recognize attributes of shapes.
Define vertex/vertices and angle.

Alabama Alternate Achievement Standards

AAS Standard:
M.AAS.7.18 Construct and analyze a geometric figure using manipulatives.

Tags:

angles, draw, geometry, protractor, sides, triangles, unique triangle

License Type:

Custom Permission Type
See Terms: https://www.engageny.org/terms-of-use
For full descriptions of license types and a guide to usage, visit :
https://creativecommons.org/licenses

Accessibility

Text Resources: Content is organized under headings and subheadings

Comments

There are eleven lessons on this topic.

This resource is free for teachers to access and use. All resources required for the lessons are available to print from the site.

This resource provided by:

Author:

Hannah Bradley

ALEX Classroom Resource

Grade 7 Mathematics Module 6, Topic B: Constructing Triangles