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,...

Students identify names of angles. They use a large clock to demonstrate angles using certain times of day. Given a geoboard, students create figures with acute, right, and obtuse angles.

Not all triangles are right! Pupils learn to tackle non-right triangles using the Law of Sines and Law of Cosines. After using the two laws, they then apply them to word problems. 

Students draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...

Through the examination of the relationship between the lengths of the sides of a triangles students will learn the classification of triangles (acute, right, or obtuse).

Building trigonometric basics here will last a mathematical lifetime. Learners expand on the previous instructional activity in a 36-part series by examining relationships between the sine and cosine of complementary angles. They...

Students find triangular angles using the angle theorem. In this geometry instructional activity, students describe labeled triangles, use the pythagorean theorem, and rewrite information about triangles in standard form.

Young scholars derive the six trigonometric functions. In this trigonometry lesson, students show their understanding of trigonometric functions as they relate the right triangles. They find the missing angles and side use trig ratios of...

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...

Students investigate triangles and their relationship to each other. In this geometry lesson, students solve right triangles using the properties of the Pythagorean Theorem. They differentiate between right, acute, straight and oblique...

Pupils explore the concept of concurrent lines in triangles. In this concurrent lines in triangles lesson, students work in groups to investigate properties of concurrent lines in acute, right, and obtuse triangles. Pupils use a...

Students use the inequality theorem to solve triangles and their properties. For this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...

Young scholars find the orthocenter of a triangle. In this geometry instructional activity, students identify where the altitudes meet in a triangle. They use Cabri software to explore acute, obtuse and right triangles.

Students apply the properties of a right triangle. In this triangle lesson plan, students describe and compare radians to degrees. They solve problems using the properties and ratios of a right triangle.

Second graders explore the features of triangles and quadrilaterals. In this lesson on triangles and quadrilaterals, 2nd graders rotate with their group to five different activities all exploring a different aspect of geometry.

Fourth graders explore obtuse triangles. In this geometry lesson plan, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.

Young scholars calculate the different sides and angles of a triangle. In this geometry lesson, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior angle...

Concepts are only valuable if they are applicable. An informative resource uses concepts developed in lessons 26 and 27 in a 36-part series. Scholars write equations and solve for missing side lengths for given right triangles....

Students identify missing sides and angles. In this geometry lesson, students use triangular theorems to identify the missing sides. They use the Pythagorean Theorem to find the different ratios of each side.

Young scholars investigate the Pythagorean Theorem. In this geometry lesson plan, students define angles and sides of right triangles. They calculate the area and surface area using formulas derived by the Pythagorean Theorem.

Learners determine the trigonometric relationships within a triangle as they construct a right triangle on the Ti-89. They find the sine, cosine, and tangent of various angles of their triangle construction.

Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry instructional activity, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles...

Students classify different types of triangles. In this geometry lesson, students identify and use properties of triangles. They differentiate between isosceles and equilateral triangles.

What does it mean for a quadrilateral to be cyclic? Mathematicians first learn what it means for a quadrilateral to be cyclic. They then investigate angle measures and area in such a quadrilateral.