This short video show viewers how to connect the sum of the angles in a triangle to other angle measurements. Pupils determine the missing measures for angles involved with triangles and quadrilaterals. Class members then must explain...

Split it down the middle. Using the tools of geometric construction, the video shows two different methods of constructing a 30-degree angle. The first method bisects an angle of an equilateral triangle. The second uses the diagonal of a...

Middle schoolers explore angle measure as they estimate angle measure and measure and draw angles of less than 360 degrees. The lesson emphasizes the use of estimation when measuring angles.

Cut it in half with a compass and straightedge! Using construction tools, a video shows how to create an angle bisector. The presenter points out what it means to bisect an angle in terms of the measure and distances from the sides of...

In this angle measurement worksheet, 10th graders solve and complete 9 different word problems. First, they read the word problems carefully. Then, students draw a picture that represents each problem and solve. Finally, they find side...

Inscribed angles are central to the instructional activity. Young mathematicians build upon concepts learned in the previous instructional activity and formalize the Inscribed Angle Theorem relating inscribed and central angles. The...

It doesn't matter whether secant lines intersect inside or outside the circle, right? Scholars extend concepts from the previous lesson to investigate angles created by secant lines that intersect at a point exterior to the circle....

Investigate relationships between angles, arcs, and segments in circles. Pupils use geometry software to discover the relationships between angles, arcs, and segments associated with circles. Class members use similar triangles to...

Noah didn't construct this kind of arc. High school scholars first explore how angles can be formed in circles. They then learn relationships between angles and arcs by conducting an exploratory activity where they position and draw arcs...

Geometry—it's not just for the math classroom! Learners explore the field of forestry through a mathematical lens. An instructional resource explains how forest workers collect data about trees such as height, diameter, and age...

High schoolers explore quadrilaterals in this geometry lesson. They will draw a quadrilateral, measure the angles, and find the sum of the measures of the interior angles using Cabri Jr. The interactive capabilities of Cabri Jr. allow...

Learn how to measure acute, right, and obtuse angles with a protractor. After reviewing the way the protractor works, fourth graders measure nine angles on their own. For extra practice, have them measure different angles in their...

Get out those protractors! Geometers measure interior and exterior angles of 10 polygons, including a 24-gon. They also calculate the interior angle sum of the polygons. 

Over the course of 18 problems, learners identify angles as complementary, supplementary, vertical or adjacent. They name relationships in angles such as alternate interior, corresponding, and alternate exterior angles. They apply the...

Angles and triangles: they're all connected. Uncover the connections between angles in triangles. Scholars learn how to find both exterior and interior angle measures in triangles. The lesson emphasizes the vocabulary related to these...

In this classification of triangles activity, 10th graders identify and complete 8 different problems that include determining the measurement and perimeter of various types of triangles. First, they color all right, acute, and obtuse...

The itsy, bitsy spider went up the virtual wall. An interactive allows users to change the angles in a spider web. They must attend to supplementary angles as they answer challenge questions throughout the interactive.

How does the number of sides of a polygon affect the angle measures? Learners recognize a pattern in finding the total measure of interior and exterior angles and the number of diagonals. They use the patterns to calculate...

Mirror, mirror on the wall, which is the fairest resource of them all? Individuals write and solve one-step equations for problems about angle measurement, including those involving mirrors. Both mathematical and real-world problems are...

Explore types of angles and the characteristics of each. After observing a PowerPoint Presentation, learners tour the school facilities and use a digital camera to capture prescribed angles. Using the digital pictures and written...

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...

All triangles have some things in common. Using these properties of triangles, learners find missing angle measures. Scholars use the Angle Sum Property and properties of special triangles throughout the lesson.

This a fun problem for young geometers to play with while gaining important insight into deductive reasoning. Some will find the answers very quickly, others might take a less direct path, but all will use their knowledge of the sum of...

Practice recognizing types of additive angles with a worksheet in which pupils review adjacent, interior and exterior, complementary, and supplementary angles and use a diagram to give examples of them. Be aware that the diagram involves...