Handout
McGraw Hill

Lines and Angles

For Students 4th - 7th Standards
Why was the obtuse angle upset? Because it was never right! A valuable resource is loaded with background information on types of angles and lines. Learners review the characteristics of parallel, perpendicular, and...
Lesson Plan
Virginia Department of Education

Lines and Angles

For Teachers 9th - 11th Standards
Explore angle relationships associated with transversals. Pupils construct parallel lines with a transversal and find the measures of the angles formed. They figure out how the different angles are related before constructing...
Lesson Plan
Curated OER

Triangle's Interior Angles

For Teachers 7th - 9th Standards
Given a pair of parallel lines and a triangle in between, geometers prove that the sum of the interior angles is 180 degrees. This quick quest can be used as a pop quiz or exit ticket for your geometry class.
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...
Lesson Plan
EngageNY

Segments That Meet at Right Angles

For Teachers 9th - 12th Standards
Can segments be considered perpendicular if they don't intersect? Learners look at nonintersecting segments on the coordinate plane and make conclusions about the lines that contain those segments. They determine if they are...
Assessment
Mathematics Assessment Project

Geometry

For Students 7th - 8th Standards
Help learners find joy in facing mathematical challenges. The questions posed on this activity encourage young mathematicians to utilize skills learned throughout a geometry unit, and to apply themselves and persevere through...
Handout
El Paso Community College

Geometry Definitions

For Students 7th - 9th Standards
Geometry is full of shapes, figures, and corresponding things here and there. The guide shares all of the key pieces of geometric information in a nicely color-coded and labeled sheet. 
Lesson Plan
1
1
Illustrative Mathematics

The Geometry of Letters

For Teachers 3rd - 5th Standards
Use the alphabet as a tool for teaching your class about geometric figures. Break apart capital letters into line segments and arcs. Classify angles as right, acute, or obtuse. Identify parallel and perpendicular lines. An excellent...
Unit Plan
1
1
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...
Lesson Plan
EngageNY

Looking More Carefully at Parallel Lines

For Students 9th - 10th Standards
Can you prove it? Making assumptions in geometry is commonplace. This resource requires mathematicians to prove the parallel line postulate through constructions. Learners construct parallel lines with a 180-degree rotation and then...
Worksheet
Lone Star College

Geometry Worksheet II

For Students 7th - 10th Standards
Young geometers get practice with the algebra of angles in an extensive skills practice worksheet. Supplementary, complementary, and vertical angle relationships are used, along with parallel lines cut by a transversal and angle sum...
Lesson Plan
2
2
Illustrative Mathematics

Shortest Line Segment from a Point P to a Line L

For Teachers 9th - 11th Standards
One of the hardest skills for many young geometers to grasp is to move beyond just declaring obvious things true, and really returning to fundamental principles for proof. This brief exercise stretches those proving muscles as the...
Worksheet
Lane Community College

Review Sheets: Geometry

For Students 8th - 11th
Full of problems with polygons, angles, lines, and triangles, your learners get a multi-page packet that provides all they need to know. It contains many of the standard problem types as well as some more challenging questions. 
Lesson Plan
EngageNY

Solve for Unknown Angles—Angles and Lines at a Point

For Teachers 9th - 10th Standards
How do you solve for an unknown angle? In this sixth installment of a 36-part series, young mathematicians use concepts learned in middle school geometry to set up and solve linear equations to find angle measures.
Worksheet
K12 Reader

Kinds of Angles

For Students 2nd - 3rd Standards
Have you ever wondered how circles and angles relate to each other? Read a passage about right angles, acute angles, and obtuse angles, and answer reading comprehension questions about the information you learn. 
Lesson Plan
EngageNY

Secant Angle Theorem, Exterior Case

For Teachers 9th - 12th Standards
It doesn't matter whether secant lines intersect inside or outside the circle, right? Scholars extend concepts from the previous lesson to investigate angles created by secant lines that intersect at a point exterior to the circle....
Lesson Plan
EngageNY

The Inscribed Angle Alternate – A Tangent Angle

For Teachers 9th - 12th Standards
You know the Inscribed Angle Theorem and you know about tangent lines; now let's consider them together! Learners first explore angle measures when one of the rays of the angle is a tangent to a circle. They then apply their...
Interactive
CK-12 Foundation

Vertical Angles

For Students 7th - 10th Standards
Examine vertical angles from a different angle. Moving one line in an intersecting pair of lines lets users see relationships between vertical angles. They finish by answering some machine-scored questions on the topic.
Worksheet
Mt. San Antonio Collage

Circles

For Students 9th - 12th Standards
Don't circle around the topic, but get right to the center with tons of practice regarding circles in geometry. The note-incorporated worksheet provides guided practice through many topics such as central angles, inscribed polygons...
Lesson Plan
EngageNY

The Definition of Sine, Cosine, and Tangent

For Students 9th - 10th Standards
Introduce your classes to a new world of mathematics. Pupils learn to call trigonometric ratios by their given names: sine, cosine, and tangent. They find ratios and use known ratios to discover missing sides of similar...
Interactive
CK-12 Foundation

Directed Line Segments: Dog Park

For Students 11th - Higher Ed Standards
Its a dog's world! Using a vector in standard position, pupils model the path a dog takes to different items in a dog park. The individuals use the interactive to find the magnitude and direction of the directed line segment.
Lesson Plan
EngageNY

Angle Sum of a Triangle

For Students 8th Standards
Prove the Angle Sum Theorem of a triangle using parallel line and transversal angle relationships. Pupils create a triangle from parallel lines and transversals. They find angle measures to show that the angles of a triangle must total...
Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
Lesson Plan
EngageNY

How Do Dilations Map Angles?

For Students 9th - 10th Standards
The key to understanding is making connections. Scholars explore angle dilations using properties of parallel lines. At completion, pupils prove that angles of a dilation preserve their original measure. 

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