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...
Curated OER
Triangles and Quadrilaterals
In this triangles and quadrilaterals worksheet, 10th graders solve 6 different problems related to using triangles and quadrilaterals in informal geometry. They determine how many lines of symmetry an equilateral triangle and an...
Curated OER
Indirect Proof and Inequalities in one Triangle
For this geometry worksheet, 10th graders complete an indirect proof and order the sides or angles of a triangle. Also, students determine if a triangle can have sides with the given lengths. The two page worksheet contains twelve...
Curated OER
Geometric Properties
Students find triangular angles using the angle theorem. In this geometry lesson, students describe labeled triangles, use the pythagorean theorem, and rewrite information about triangles in standard form.
Curated OER
Geometry Worksheet: Angle (2)
In this geometry worksheet, students find the measure of missing angles. They identify alternate angles. This one-page worksheet contains two problems.
Curated OER
Triangles
In this triangles worksheet, 10th graders solve and complete 22 different problems related to various types of triangles. First, they name the shortest and longest sides and the smallest and largest angles in each of triangles...
Inside Mathematics
Hopewell Geometry
The Hopewell people of the central Ohio Valley used right triangles in the construction of earthworks. Pupils use the Pythagorean Theorem to determine missing dimensions of right triangles used by the Hopewell people. The assessment task...
Curated OER
Identify Angles
In this angles practice worksheet, students respond to 4 questions that require them to identify the pictured angles as acute, right, or obtuse triangles.
Curated OER
Angle Exploration and Classification
Young scholars compare and contrast angles and identify them as acute, obtuse, right, or straight angles. They create rays and angles using uncooked spaghetti, read and discuss key vocabulary terms, and complete a variety of geometry...
Curated OER
Identify Angles: Obtuse, Right, Straight and Acute
In this triangle worksheet, students identify angles as either obtuse, right, straight or acute. A reference web site is given for additional activities.
Curated OER
Basic Right Triangles
Elementary schoolers examine the attributes of triangles. In this triangle lesson, learners compare regular triangles and right triangles. They explore vertices and angles and investigate obtuse and acute angles. Pupils draw multiple...
PBS
Accessible Shapes
All the 2-D and 3-D measurement work you need is in one location. Divided into three sections, the geometry lesson plans consist of visualization of three dimensions, classifying geometric figures, and finding surface area and volume....
EngageNY
End-of-Module Assessment Task - Geometry (module 2)
Increase the level of assessment rigor with the test of performance tasks. Topics include similar triangles, trigonometric ratios, Law of Sines, Law of Cosines, and trigonometric problem solving.
Curated OER
Informal Geometry
Middle and high schoolers solve and complete 29 various types of problems. First, they match each name with its correct formula. Then, students find the length of the missing side and the distance between the two points given. In...
Curated OER
The Greedy Triangle-Intro to Geometric Shapes
In this geometry lesson, learners read The Greedy Triangle and use geoboards to construct geometric shapes. They identify the number of sides and angles each shape has.
Curated OER
Right Triangles
In this right triangles worksheet, 10th graders solve and complete 12 different types of problems. First, they solve for a variable given each of the right triangles with the sides as indicated. Then, students determine the shorter...
Curated OER
Independent Practice 2: Triangles
In this triangle activity, students identify given triangles according to their sides and angles. Afterward, students draw triangles to match given descriptions. This one-page activity contains 15 problems.
Math Mammoth
Triangles
A six-page packet walks, or bends learners through angles that combine to create triangles. Definitions are given for right triangles, obtuse and acute triangles. They draw angles according to directions, using a protractor to meet the...
EngageNY
The Definition of Sine, Cosine, and Tangent
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...
EngageNY
Incredibly Useful Ratios
Start the exploration of trigonometry off right! Pupils build on their understanding of similarity in this lesson that introduces the three trigonometric ratios. They first learn to identify opposite and adjacent...
Willow Tree
Common Geometric Figures
Geometry could be called the study of figures. An overview of the figures found in a typical geometry course contains a study of different triangles, quadrilaterals, and regular polygons.
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...
K-5 Math Teaching Resources
2-D Shape Cards
Add some visual support to your elementary geometry lessons with this set of printable shape cards. From triangles and squares to octagons and nanogons, this simple resource can be used in countless ways to develop children's knowledge...
CK-12 Foundation
Ambiguous Case: Furniture Store Problems
Remove any ambiguity about using a helpful resource. Individuals use an interactive to find the number of triangles that fit given conditions. They find that some conditions can result in more than one triangle in the ambiguous case.