EngageNY
Congruence Criteria for Triangles—ASA and SSS
How do you know if a pair of triangles are congruent? Use the lesson to help class members become comfortable identifying the congruence criteria. They begin with an exploration of ASA and SSS criteria through transformations and...
EngageNY
The Side-Angle-Side (SAS) and Side-Side-Side (SSS) Criteria for Two Triangles to Be Similar
Playing with mathematics can invoke curiosity and excitement. As pupils construct triangles with given criteria, they determine the necessary requirements to support similarity. After determining the criteria, they practice...
Bowland
Rods and Triangles
Scholars explore triangles with rods of different lengths. Using rods of 2, 4, 6, 8, and 10 cm class members build as many different types of triangles as they can. They also describe properties of these triangles and determine...
Mathematics Assessment Project
Applying Angle Theorems
Polygon ... an empty bird cage? After finding the angles of a polygon, young mathematicians use the provided methods to solve the problem in multiple ways.
EngageNY
Unknown Angle Proofs—Proofs of Known Facts
Lead the class in a Greek history lesson 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...
Curated OER
Relationship between Exterior and Remote Interior Angles in a Triangle
In this triangle worksheet set, 9th graders find the relationship between the exterior and remote interior angles in triangles. They determine the formula, and apply it in 15 problems. They use a compass as needed to measure angles.
Curated OER
Angle Sum of Triangles and Quadrilaterals
In this angle sum worksheet, students find missing angles of 20 triangles and quadrilaterals. Students find the missing angle in each polygon by using the total degrees of each and given angle measures.
Curated OER
Geometry Worksheet- Angle
In this geometry learning exercise, students solve questions dealing with angles, triangles, and quadrilaterals. They calculate the missing angle. There are 2 questions.
Curated OER
Triangle Angle-Sum Theorem
In this polygons instructional activity, students fill out a graphic organizer about the name of the polygon, the number of sides, the angle sums, and more. Students complete this for 5 polygons.
Curated OER
Classifying Triangles Based On Properties of Angles
The interactive lesson plan featured here calls for the use of a Smartboard for sorting and classifying shapes. Then, pupils discuss the rules they followed for sorting their shapes, particularly focusing on the properties of angles....
Curated OER
Simple Angles
Third graders identify and construct right, acute and obtuse angles and begin to appreciate the degree and unit of measurement of angle. They know the degree value of angles that are simple fractions of a whole turn know that the angle...
Curated OER
Special Triangles and Quadrilaterals
In this special triangles learning exercise, students examine given special triangles. They determine the length of a missing side and/or the measurement of a missing angle for given triangles and quadrilaterals. Students...
Curated OER
Exploring Characteristics of Triangles
Learners draw triangles and explore the classification of each using the measures of interior angles and lengths of sides. They investigate the sum of the interior angles of various triangles and conjecture and prove the theorem: The...
Curated OER
Interior Angles of Regular Polygons
High schoolers investigate the interior angles of a triangle. In this geometry lesson, students create the formula to calculate the angles inside a triangle. They observe the total sum of a triangles angle on the navigator.
Curated OER
Basic Trigonometric Ratios
In this trigonometric ratio worksheet, learners determine the length of a side of a right triangle, or the measurement of angles using trigonometric ratios. This one-page worksheet contains 24 problems. Answers are provided at the bottom...
CK-12 Foundation
Angle-Side-Angle Triangles: Caution Tape
Don't lose your marbles. Scholars use an interactive to create a triangle that closes off a portion of a sidewalk with loose marbles. The Law of Sines helps them find the side measures of such a triangle.
Mathematics Vision Project
Geometric Figures
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
Curated OER
Triangles
In this triangles worksheet, students solve six word problems where they determine the angles measures in different triangles.
Curated OER
Measuring Angles in a Triangle
High schoolers investigate the sum of the measures of the angles of a triangle. They draw a triangle and measure the interior angles. Using Cabri Jr., learners find the sum of the measures of the interior angles. The instructional...
Curated OER
Determine the Measure of an Angle of a Right Triangle.
In this geometry worksheet, learners solve word problems by finding the values of missing angles and missing sides of triangles. They review their trigonometric properties of a right triangle. There are 9 problems with an answer key.
Curated OER
Travel Triangles
Students demonstrate and understanding of the three types of angles using triangles and quadrilaterals. In this angles lesson plan, students learn about acute, obtuse and right angles. They use cut-outs to find the areas of triangles and...
Curated OER
Angles, Triangles, Quadrilaterals, Circles and Related
Students classify angles. For this angles lesson, students explore the characteristics of angles, triangles, quadrilaterals and circles. They identify polygons and sing a classifying angles song. Students participate in a manipulative...
Curated OER
Triangle Inequality Theorem
High schoolers investigate the relationship between angle measures and sides of a triangle and the relationships among the three sides of a triangle. The use of technology (Cabri, Jr.) allows learners to make and test conjectures as they...
Curated OER
Finding the Sum of the Exterior and Interior Angles of a Polygon
Students find the sum of the angles of a polygon and construct a polygon given the number of sides. In this polygon lesson plan, students draw large polygons on the floor of the room. They measure the length of each side and the interior...