Students practice various equations for constructing nine-point circles for triangles.

In this triangle proofs worksheet, high schoolers answer 5 questions about triangles and polygons given certain information. Students then construct 4 triangle or polygon proofs.

Add up areas of squares to discover the pythagorean relationship. Small groups create right triangles with squares along each side. They calculate the areas of each square and notice the relationship. Groups construct other types of...

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...

Just what does it take to show two rhombuses are similar? The assessment task asks pupils to develop an argument to show that given quadrilaterals are rhombuses. Class members also use their knowledge of similar triangles to show two...

Here's some very interesting circles for your very interested pupils. A performance task requires scholars to sketch a pair of orthogonal circles so the centers are the endpoints of one side of a triangle. They draw an additional circle...

Have you hit a wall when trying to create performance task questions? Several open-ended response questions require a deep level of thinking. Topics include triangle congruence, quadrilaterals, special segments, constructions, and...

Young mathematicians build an understanding of area and perimeter with their own two hands in a series of interactive geometry lessons. Through the use of different math manipulatives, children investigate the properties of...

Gaining practice in translating a verbal description into a diagram and then an equation is the real point of this similar triangles exercise. Once the diagram is drawn, multiple methods are provided to reach the conclusion. An effective...

While it may seem incredibly obvious to the geometry student that congruent sides make congruent triangles, the proving of this by definition actually takes a bit of work. This exercise steps the class through this kind of proof by...

Class members complete an assessment task by identifying whether statements about triangles and quadrilaterals are always true, sometimes true, or never true. They then participate in a sorting activity with the same objective.

Challenge scholars to show what they know about properties and addition and subtraction formulas for trigonometric functions. The resource provides a mid-unit check on the progress toward mastery of trigonometric concepts. The areas...

For this geometry worksheet, learners construct polygons and calculate the different angles formed by each shape. They construct circles, trapezoids, and rectangles and answer 20 questions.

Properties about triangles are explored in this lesson. Geometers make conjectures about the length of a triangle's sides, the length of the angles in relation to the length of the sides, and the measure of the exterior angles of a...

Second graders create a fact family town to develop the understanding of numbers related in fact families. They learn each family has a big number and two baby numbers. They make triangle shaped houses for their facts.

Learners explore the measures of the angles of a triangle in this geometry instructional activity. They use Cabri Jr. to investigate the sum of the measures of the interior angles of a triangle, and examine the relationships between the...

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...

Learners construct the Sierpinski Triangle using Cabri Jr. They use a step-by-step guide to construct the Sierpinski Triangle on their graphing calculator and then discuss the formula for constructing a nth stage Sierpinski Triangle.

In this math learning exercise, learners are asked to used a compass and straight edge to construct copies of shapes, angles and line segments.

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

In this proofs activity, students construct 1 proof of the law of cosines.  Students construct a right triangle within a circle to  prove the law of cosines.

In this refraction through a triangle worksheet, students use a given diagram of light striking a triangular piece of plexiglass to determine the light ray's angle of incidence, the ray's angle of refraction, they use Snell's Law to...

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

Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. For this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how...