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
Identifying Angles
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.
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Toothpick Triangles
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...
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...
Curated OER
The Pythagorean Theorem and Classifying Triangles
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).
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Geometric Properties
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.
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Orthocenter Of a Triangle
Students 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.
Curated OER
Pythagorean Theorem: Triangles and Their Sides
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...
Curated OER
Concurrent Lines in Triangles
Students explore the concept of concurrent lines in triangles. In this concurrent lines in triangles lesson plan, students work in groups to investigate properties of concurrent lines in acute, right, and obtuse triangles. Students use a...
Curated OER
Angle-Side Relationships
Students calculate the different sides and angles of a triangle. For this geometry lesson, students use triangular properties to define the relationship between two triangle. They identify missing angles using the interior angle theorem.
Curated OER
Triangle Inequality Theorem
Learners use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
Curated OER
Review of Triangles
Students investigate the Pythagorean Theorem. In this geometry lesson, students define angles and sides of right triangles. They calculate the area and surface area using formulas derived by the Pythagorean Theorem.
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Obtuse Triangles
Fourth graders explore obtuse triangles. In this geometry lesson, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.
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Geometry and Measurement
Middle schoolers view a right triangle displayed by the teacher. Students measure legs and the interior angles of the triangle. They look for a pattern or relationship between the legs and angles. Middle schoolers use pegboards and...
Curated OER
Triangle Side Lengths and Angles Measures
Learners 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.
Curated OER
Pythagorean Relationships
Oh that Pythagorean Theorem is so useful. Learners engage in a 45 minute learning activity that requires them to solve for missing angles and sides of a right triangle. They'll use the Pythagorean Theorem to find the rations of sides and...
Curated OER
Triangle Classification
High schoolers classify different types of triangles. In this geometry lesson, students identify and use properties of triangles. They differentiate between isosceles and equilateral triangles.
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Angles in Triangles
Eighth graders translate word problems using mathematical ideas. For this geometry lesson, 8th graders identify angles of triangles using equations and the triangle sum theorem. They create angles with a protractor and straight edge.
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Pythagorean Theorem
Learners find the different ratios of a triangle. In this geometry lesson, students use the Pythagorean Theorem to solve for missing sides and angles on a right triangle. They use a robot to create a right triangle.
Curated OER
Studying Special Segments in Triangles
Learners investigate special segments in triangles. In this geometry lesson, students graph, compare, estimate and predict findings based on their data. They differentiate between similarity and congruence of triangles.
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Pythagorean Theorem
Students investigate the properties and idea of the Pythagorean Theorem. In this algebra activity, students identify the different parts of a right triangle and relate it to the Pythagorean Theorem. They do a robotic experiment to...
Curated OER
Pythagorean Theorem
Students explore the history of Pythagoras and his contributions to mathematics. For this middle school geometry lesson, students use one inch tiles to investigate the Pythagorean Theorem and to find the length of the sides of a right...
Curated OER
Pythagorean Theorem by Graphic Manipulation
There are many different ways to show a proof of the Pythagorean Theorem. Here is a nice hands-on paper cutting activity that shows a graphic representation. You can even challenge your young Pythagoreans to come up with their own...
Curated OER
Making Tangram Pieces by Folding Paper
Third graders follow directions to make a set of tangram pieces. After reading a story, they compare and contrast the differences between two-dimensional shapes. To end the lesson plan, they use the tangram pieces to create their own...