Illustrative Mathematics
Are These Right?
Is that a right triangle or a wrong triangle? Young mathematicians look at eleven different shapes and use a measuring tool of their choice to determine which triangles have right angles. Consider cutting out sets of the shapes to...
Curated OER
Angles
Fourth and fifth graders investigate angles and name them according to the criteria for obtuse, acute, and right angles. They examine a human-made yarn pattern on the floor of their classroom and identify angles, vertices, and types of...
Utah Education Network (UEN)
Angles, Degrees, Protractors . . . Oh My!
Fourth and fifth graders make a protractor and identify various angle types. In this protractor and angle lesson, learners make their own protractor and use it to measure a variety of angles. They complete worksheets while identifying...
Mathematics Vision Project
Similarity and Right Triangle Trigonometry
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...
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
Curated OER
An Introduction to Angles
Students identify and create angles. In this angle measurement lesson plan, students use sticks to make models of angles, then measure and name each angle.
CK-12 Foundation
Angle Classification: Angle Exploration
Acute or obtuse? Seems right to me! As scholars explore the simulation, they investigate angle measures. Questions ask them to classify the angles using correct naming conventions.
Curated OER
What is my Angle? App
Learners estimate angle measures in this this estimating angle measures instructional activity. They use an application on their graphing calculator that shows various settings involving angles and then they estimate the angle measure of...
EngageNY
Inscribed Angle Theorem and Its Applications
Inscribed angles are central to the lesson. Young mathematicians build upon concepts learned in the previous lesson and formalize the Inscribed Angle Theorem relating inscribed and central angles. The lesson then guides learners to prove...
Curated OER
Sample Lesson Plan on Lines and Angles
Student complete worksheet using the definitions of lines and angle vocabulary. They define the word and follow a direction given on the worksheet such "construct a line." They complete an online tutorial on how to measure angles using a...
EngageNY
Angle Sum of a Triangle
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...
EngageNY
More on the Angles of a Triangle
Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...
CK-12 Foundation
Angle Classification: Crazy Quilt
There's more to a quilt than just a pretty pattern—there's geometry! Explore angle classification using an artistic approach to show your class that quilt designs are really just intricate geometric patterns. Here, scholars create a...
Curated OER
Measuring Angles
Middle schoolers explore angle measure as they estimate angle measure and measure and draw angles of less than 360 degrees. The lesson emphasizes the use of estimation when measuring angles.
Curated OER
Angle Relationships
Students investigate geometric relationship using conjecture about linear pairs and vertical angles. In this geometry lesson, students apply their theorems and previous geometry knowledge to solve for and find angles of linear pairs....
Curated OER
Measuring Angles in a Quadrilateral
High schoolers explore quadrilaterals in this geometry lesson. They will draw a quadrilateral, measure the angles, and find the sum of the measures of the interior angles using Cabri Jr. The interactive capabilities of Cabri Jr. allow...
Alabama Learning Exchange
Unit Circle: Special Angles—Just Know One
It's all about the patterns! Young scholars learn that the unit circle repeats itself in all four quadrants. Using these patterns, they evaluate the sine, cosine, and tangent of special angles.
EngageNY
Sine and Cosine of Complementary Angles and Special Angles
Building trigonometric basics here will last a mathematical lifetime. Learners expand on the previous lesson in a 36-part series by examining relationships between the sine and cosine of complementary angles. They also review the ratios...
EngageNY
Unknown Angle Proofs—Proofs with Constructions
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...
CK-12 Foundation
Angles: The Angle of Discovery
Practice important angle vocabulary using an interactive lesson. As learners manipulate vertical angles, they watch the supplementary and congruent angles adjust. Questions pertaining to vocabulary and measurements follow their exploration.
CK-12 Foundation
Angle Classification: Angles in the Game of Pool
Make a game of angle classification. Using the direction of the pool ball, scholars determine the measure of the created angles. They work to create and classify different types of angles throughout an engaging interactive.
Curated OER
Investigating Segments in a Right Triangle
High schoolers explore the concept of right triangles as they construct a right triangle using Cabri Jr. Learners find the midpoint of the hypotenuse and construct a line from the midpoint to the vertex of the right angle. They then...
Mathematics Vision Project
Circles: A Geometric Perspective
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
Curated OER
Similarity and Dilations - Discover Properties of Similar Figures
Learners investigate properties of similar figures. In this properties of similar figures lesson, pupils construct similar figures using Cabri Jr. They dilate their figure to create a similar one, and discuss the relationships between...