Teach your class how to apply their knowledge of geometry as they explore the unknown. In order to find an unknown angle, students must understand that rectangles have four interior right angles, that right angles have 90 degrees, and...

Given a pair of parallel lines and a triangle in between, geometers prove that the sum of the interior angles is 180 degrees. This quick quest can be used as a pop quiz or exit ticket for your geometry class.

Is that a right triangle or a wrong triangle? Young mathematicians look at eleven different shapes and use a measuring tool of their choice to determine which triangles have right angles. Consider cutting out sets of the shapes to...

How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Learners are asked to divide the...

This one activity requires young geometers to pull together information they are currently learning with things they have learned previously. Here they rely on understanding something about parallel lines, alternative interior angles,...

After learning that the sum of interior angles for triangles is 108 degrees, take it further to show that the sum of angles in any polygon is the same! Using hexagons, pupils practice finding the measure of the six congruent angles. Make...

Rays and angles and Star Wars? It sounds strange, but it's actually a fun game to help fourth graders get good at measuring and identifying angles and rays with a protractor. Each pair of children chooses which Star Wars character they'd...

Boat ramps move with waves and changes in water level. Scholars decide on the proper length for a ramp so the angle connecting both sides is appropriate. They visualize the situation and use a simulation to view the results with their...

Bringing together the young artists and the young organizers in your class, this lesson takes that popular topic of tessellations and gives it algebraic roots. After covering a few basic properties and definitions, learners attack the...

Your geometry learners explore Angle-Side-Angle congruence in this collaborative task. The sum of the interior angles of all triangles being one hundred eighty degrees, is the key learners will discover as they explain their reasoning...

A basic set-up leads to a surprisingly complex analysis in this variation on the question of surrounding a central circle with a ring of touching circles. Useful for putting trigonometric functions in a physical context, as well as...

The class gets to practice being a mathematician in ancient Greece, performing geometric application problems in the way of Eratosthenes. After following the steps of the great mathematicians, they then compare the (surprisingly...

This activity is a follow-on activity to inscribing a square in a circle. The overall problem is more complex. It deals with geometric constructions, properties of triangles, and regular hexagons. The final part of the activity...

You can pick up some valuable pointers on angles and lines here. When you finish working your way through the pages you can take an on-line "Test Bite," and check your understanding.

Here is a site that clearly and thoroughly explains many topics regarding measurement of angles, including standard position, degree measure, and coterminal angles. There are example problems solved, problems for the student to attempt,...

Sharpen your logic and angle recognition skills by working on this interactive challenge. Solution available.

Here is a site that clearly and thoroughly explains the radian measure of angles. There are example problems solved, problems for the student to attempt, and answers to the student problems.

This very basic website gives a clear, simple explanation of what an acute angle is.

Students construct a line parallel to the base of a triangle and measure the angles formed. They use the construction to prove that the sum of the measures of the interior angles of a triangle is 180 degrees.

Students will expore the interior and exterior angle of 3 polygons and develop the formula to calculate the sum of degrees without the measurement of the angles being taken.

This math tutorial provides an illustrated explanation of a reflex angle.

Sharpen your logic, time, and angle recognition skills while working on this challenge. The solution is available to double check your results. (Hint: Use the "90 degree" right angle button on the clock to check if something is a right...

Angles are key to Trigonometry. Learn definitions of the parts of an angle, degrees, and radians, identify the standard position of an angle, convert between radians and degrees, and more.

In this activity using the USA TODAY Snapshot, "Coming clean about showering time," students will find the measures of central angles and arcs of a circle. They will use circumference, radius, concentric circles and degrees in a circle...