Curated OER
Geometry: Classifying Angles
Pupils measure, construct, and classify angles as acute, right, straight, and obtuse. Once they have completed an angle worksheet, students use a map of South Carolina to locate cities by constructing the aforementioned angles.
Shodor Education Foundation
Shodor Interactivate: Lesson: Angles (Elementary)
In this lesson students will learn what determines whether an angle is acute, obtuse or a right angle.
Beacon Learning Center
Beacon Learning Center: Anglemania!
Students explore four types of angles in this interactive web lesson.
Beacon Learning Center
Beacon Learning Center: Triangles Side by Side
This comprehensive web lesson describes how to classify triangles by their angle and side measurements. It provides real-world examples and exercises for students to practice the skill.
University of Saskatchewan (Canada)
University of Saskatchewan: Trigonometric Functions
This site examines the six trigonometric functions from a right triangle point of view. Provides information, examples, and lots of exercises for understanding.
Oswego City School District
Regents Exam Prep Center: Geometry Vocabulary Resources
A list of geometry definitions and a matching activity.
Cuemath
Cuemath: Obtuse Triangle
In this mini-lesson, learn about obtuse triangles including the obtuse triangle definition, sides, properties, examples, and other fun facts related to it.
Math.com
Math.com: Building Blocks: Classifying Angles
This geometry resource investigates types of angles. Definitions, detailed examples, and practice problems are included.
Wolfram Research
Wolfram Math World: Cut the Knot! Angles
Very good site with links to reviews of various angles.
Wolfram Research
Wolfram Math World: Obtuse Triangles
MathWorld.com offers information on obtuse triangles and links to related terms and formulas.
Shodor Education Foundation
Shodor Interactivate: Angles
The activity allows students to practice identifying different types of angles. An interactive activity and teacher resources are included.
Texas Instruments
Texas Instruments: Classifying Angles
Students will create a variety of angles using the Geoboard APP. The teacher will use Screen Capture to display the angles created by the students and will lead a discussion on whether the angles are acute, right, or obtuse.
Homeschool Math
Homeschool Math: Triangles
This lesson plan provides students with an opportunity to practice drawing and measuring triangles and angles. It also shows pictures and gives definitions of each type of angle and triangle.
CK-12 Foundation
Ck 12: Elem Math: Classifying Triangles Within Composite Figures
[Free Registration/Login may be required to access all resource tools.] In this learning module, students are presented with a composite figure and must identify the types of triangles within it. An accompanying video demonstrates a...
Math Is Fun
Math Is Fun: Angles
Definitions of different types of angles along with images and an interactive tool through which you can create acute, right, straight, obtuse, and reflex angles. View the parts of an angle, and learn the proper way to label angles.
Varsity Tutors
Varsity Tutors: Hotmath: Graphing Calculator Practice Problems: Point, Line, Planes, Angles
Practice using your graphing calculator for drawing and labeling points, lines, planes, and angles. If you get stumped or if you would like to check your work, then select the View Solution button, which is located directly under each...
CK-12 Foundation
Ck 12: Angle Classification
[Free Registration/Login Required] Students explore classifying angles by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more about the concept by...
CK-12 Foundation
Ck 12: Volume of Pyramids: Angle Exploration
[Free Registration/Login Required] Students explore classifying angles by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more about the concept by...
CK-12 Foundation
Ck 12: Volume of Pyramids: Right Angles in a Game of Pool
[Free Registration/Login Required] Students explore classifying angles by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more about the concept by...
CK-12 Foundation
Ck 12: Geometry: Angle Classification Intermediate
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to classify angles based on their measure.
CK-12 Foundation
Ck 12: Elem Math: Counting Right Angles in a Diagram
[Free Registration/Login may be required to access all resource tools.] Practice counting the number of right angles in a diagram in this learning module. Includes video demonstration of a sample problem [2:11] and practice questions.
CK-12 Foundation
Ck 12: Geometry: Angle Classification Grade 6
[Free Registration/Login may be required to access all resource tools.] Classify acute, right, obtuse, and straight angles.
Math Is Fun
Math Is Fun: Interactive Triangles
This is an excellent tool for students to explore how changes in the size of a triangle's sides or angles affect its appearance. Different types of triangles and angles are presented.
Math Open Reference
Math Open Reference: Angle Quiz
Students are assessed on different types of angles. Definitions of the angles are included.