Curriculum / Math / 7th Grade / Unit 6: Geometry / Lesson 14
Math
Unit 6
7th Grade
Lesson 14 of 21
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Lesson Notes
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Identify unique and identical triangles.
The core standards covered in this lesson
7.G.A.2 — Draw (freehand, with ruler and protractor, and with technology) geometric shapes with given conditions. Focus 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.
The essential concepts students need to demonstrate or understand to achieve the lesson objective
Suggestions for teachers to help them teach this lesson
In Lessons 14 and 15, students investigate the situations that create unique, more than one, or no triangle. In this lesson, students observe how the conditions described about a triangle can sometimes be represented in a diagram in different ways. They will begin to sketch triangles with given conditions and continue this in Lesson 15.Â
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Problems designed to teach key points of the lesson and guiding questions to help draw out student understanding
25-30 minutes
Examine this set of triangles.
a. What is the same about the triangles in the set? What is different?
b. How many different triangles are there? Explain or show your reasoning.
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Grade 7 Unit 7 is made available by Open Up Resources under the CC BY 4.0 license. Copyright © 2017 Open Up Resources. Download for free at openupresources.org. Accessed March 11, 2018, 12:12 p.m..
Phil, Raul, and Teresa each drew a right triangle with another angle measuring 30° and a side length of 4 inches. Their drawings are shown below (not drawn to scale).
Phil claims that he drew the same triangle as Raul, but different from Teresa. Do you agree with Phil? Explain why or why not.
A set of suggested resources or problem types that teachers can turn into a problem set
15-20 minutes
Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.
A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved
5-10 minutes
A triangle has side lengths 8 cm and 3 cm and one angle that measures 20°.
a. Draw and label two triangles that have the measurements above and are the same triangle.
b. Draw and label a triangle that has the measurements above but is different from the triangle you drew in part (a).
The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.
Next
Determine if conditions describe a unique triangle, no triangle, or more than one triangle.
Topic A: Angle Relationships
Identify and determine values of angles in complementary and supplementary relationships.
Standards
7.G.B.5
Use vertical, complementary, and supplementary angle relationships to find missing angles.
Use equations to solve for unknown angles. (Part 1)
Use equations to solve for unknown angles. (Part 2)
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Topic B: Circles
Define circle and identify the measurements radius, diameter, and circumference.
7.G.B.4
Determine the relationship between the circumference and diameter of a circle and use it to solve problems.
Solve real-world and mathematical problems using the relationship between the circumference of a circle and its diameter.
Determine the relationship between the area and radius of a circle and use it to solve problems.
Solve real-world and mathematical problems using the relationship between the area of a circle and its radius.
Solve problems involving area and circumference of two-dimensional figures (Part 1).
7.G.B.47.G.B.6
Solve problems involving area and circumference of two-dimensional figures (Part 2).
Topic C: Building Polygons and Triangles
Draw two-dimensional geometric shapes using rulers, protractors, and compasses.
7.G.A.27.G.B.5
Determine if three side lengths will create a unique triangle or no triangle.
7.G.A.2
Topic D: Solid Figures
Identify and describe two-dimensional figures that result from slicing three-dimensional figures.
7.G.A.3
Find the surface area of right prisms.
7.G.B.6
Find the surface area of right pyramids.
Find the volume of right prisms and pyramids.
Solve real-world and mathematical problems involving volume.
Distinguish between and solve real-world problems involving volume and surface area.
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