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Unit Plan
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EngageNY

Congruence, Proof, and Constructions

For Teachers 8th - 10th Standards
This amazingly extensive unit covers a wealth of geometric ground, ranging from constructions to angle properties, triangle theorems, rigid transformations, and fundamentals of formal proofs.  Each of the almost-forty lessons is broken...
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Lesson Plan
EngageNY

Informal Proofs of Properties of Dilations

For Teachers 8th Standards
Challenge the class to prove that the dilation properties always hold. The lesson develops an informal proof of the properties of dilations through a discussion. Two of the proofs are verified with each class member performing the...
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Lesson Plan
EngageNY

Angles Associated with Parallel Lines

For Students 8th Standards
Explore angle relationships created by parallel lines and transversals. The 13th lesson of 18 prompts scholars use transparency paper to discover angle relationships related to transversals. Learners find out that these angles pairs are...
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Lesson Plan
EngageNY

Unknown Angle Proofs—Proofs of Known Facts

For Teachers 9th - 10th Standards
Lead the class in a Greek history activity with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete practice...
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Lesson Plan
EngageNY

Unknown Angle Proofs—Proofs with Constructions

For Teachers 9th - 10th Standards
Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...
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Handout
Charleston School District

The Sum of Angles in a Triangle

For Students 8th Standards
An informative lesson contains a brief explanation of how the sum of the angles of a triangle is a line. The lesson continues with determining the missing angle in a triangle, or solving for a variable. Using the sum of the angles, the...
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Lesson Plan
EngageNY

Similarity and the Angle Bisector Theorem

For Teachers 9th - 10th Standards
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
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Lesson Plan
West Contra Costa Unified School District

Arcs and Angles

For Teachers 9th - 12th
Noah didn't construct this kind of arc. High school scholars first explore how angles can be formed in circles. They then learn relationships between angles and arcs by conducting an exploratory activity where they position and draw arcs...
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Lesson Plan
Virginia Department of Education

Angles, Arcs, and Segments in Circles

For Teachers 9th - 11th Standards
Investigate relationships between angles, arcs, and segments in circles. Pupils use geometry software to discover the relationships between angles, arcs, and segments associated with circles. Class members use similar triangles to...
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Lesson Plan
Virginia Department of Education

Properties of Quadrilaterals

For Teachers 9th - 11th Standards
What type of quadrilateral is that? Discover the difference between the types of quadrilaterals. Small groups investigate types of quadrilaterals using geometry software to find their properties. To keep track of the different...
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Worksheet
Mt. San Antonio Collage

Properties of a Parallelogram

For Students 9th - 12th Standards
More than just a worksheet, the resource provides a thorough guide to navigate through the land of parallelograms. Filled with definitions and theorems, the resource supports learners through problems such as proofs and finding missing...
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Worksheet
Mt. San Antonio Collage

Postulates, Angles, and Their Relationships

For Students 8th - 11th Standards
More than a worksheet, learners go through geometry topics example by example on the nicely organized handout. From postulates to classifying angles, there are rules and examples provided for each topic. The ten pages of problems provide...
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Instructional Video12:02
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Flipped Math

Properties of Parallel Lines

For Students 9th - 12th Standards
Work within a parallel universe. Scholars learn about the relationships of angles when two parallel lines are intersected by a transversal. They see how to find the measurements of all eight angles by knowing the measure of one angle....
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Lesson Plan
Curated OER

Interactivate - Lines, Rays, Line Segments, and Planes

For Teachers 6th - 8th
Young scholars explore lines, rays, line segments, and planes. For this math lesson, students discuss the math concepts and direct their instructor in graphing functions. Young scholars collaborate in graphing additional functions.
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Lesson Plan
Curated OER

Similar Situations

For Teachers 3rd - 6th
Students explore intersecting lines. In this intersecting lines lesson, students investigate shapes consisting of parallel, perpendicular, and similar lines. Students investigate these lines in shapes around them.
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Lesson Plan
Curated OER

Hypatia: Angles

For Teachers 6th - 7th
Introduce your young geometers to Hypatia, the first noted Greek female mathematician, and the properties of angles. Though this resource is missing worksheets that are needed to complete the lesson, the structure is sound and learning...
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Worksheet
Curated OER

Properties of Angles, Lines, and Triangles

For Students 10th
In this properties of angles, lines and triangles worksheet, 10th graders solve and complete 28 different problems that include determining the measurement of various figures shown. First, they use the geometric properties and theorems...
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Lesson Plan
EngageNY

Solve for Unknown Angles—Angles in a Triangle

For Teachers 9th - 10th Standards
Assist your class with each angle of geometry as they use exterior angles to form linear pairs with adjacent interior angles. They cover multiple vocabulary terms and work practice problems, complete with justifications, before taking an...
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Lesson Plan
Willow Tree

Angle Sum Property of Triangles

For Students 8th - 11th Standards
All triangles have some things in common. Using these properties of triangles, learners find missing angle measures. Scholars use the Angle Sum Property and properties of special triangles throughout the lesson.
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Lesson Plan
EngageNY

Properties of Dilations

For Teachers 8th Standards
Investigate dilations to learn more about them. The second segment in a series of 16 provides a discussion of properties of dilations by going through examples. The problem set provides opportunities for scholars to construct dilations.
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Lesson Plan
EngageNY

Solve for Unknown Angles—Transversals

For Teachers 9th - 10th Standards
Lead your class on an exciting journey through the world of math as they review geometry facts and solve for unknown angles. They learn how to use auxiliary lines and congruent angles to correctly complete each practice problem...
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Unit Plan
1
1
Mathematics Vision Project

Similarity and Right Triangle Trigonometry

For Teachers 10th - 12th Standards
Starting with similar triangles and dilation factors, this unit quickly and thoroughly progresses into the world of right triangle features and trigonometric relationships. Presented in easy-to-attack modules with copious application...
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Lesson Plan
EngageNY

Special Lines in Triangles (part 1)

For Students 9th - 10th Standards
Allow your pupils to become the mathematicians! Individuals explore the properties of a midsegment of a triangle through construction and measurement. Once they figure out the properties, learners use them to draw conclusions.
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Lesson Plan
Willow Tree

Interior Angles, Exterior Angles, and Diagonals of Polygons

For Students 8th - 11th Standards
How does the number of sides of a polygon affect the angle measures? Learners recognize a pattern in finding the total measure of interior and exterior angles and the number of diagonals. They use the patterns to calculate the number of...