Inscribing a square in a circle brings up a number of interesting geometry topics including triangle congruence and how to prove a quadrilateral is a square. This activity is followed up by finding the area of the square and determining...

Right triangles from 2,000 years ago? Learners investigate different right triangles found in the earthworks of the Hopewell people, a Native American culture that populated the United States from 200BC to AD 500. Learners apply concepts...

Construct tangent lines and make the connection to tangent functions. An informative lesson reviews the geometry origins of the tangent function. Pupils use that information to determine how to construct a tangent to a circle from a...

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...

Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...

Can it be constructed? The task poses the question whether it is possible to have an equilateral triangle with its vertices located at integer coordinates. Pupils work with their knowledge of trigonometric ratios and the Pythagorean...

Young geometers and biologists investigate the math of nature in an activity that is just the bee's knees. Participants will study the tessellations of hexagons in a beehive, along with the natural rationale behind the specific shape....

Need an activity for teaching the Pythagorean Theorem? Geometry juniors apply the Pythagorean theorem to two triangles to determine a final calculation. 

High School geometers verify through experimentation certain properties about dilations. This multi-step problem challenges them to construct examples of dilations to verify specific facts, the final step provides an opportunity to more...

Learners see application of construction techniques in a short but sophisticated problem. Combining the properties of inscribed triangles with tangent lines and radii makes a nice bridge between units, a way of using...

How can you formally assess understanding of circle concepts? Pupils take a mid-module assessment containing five questions, each with multiple parts.

What does slope have to do with lines? Pupils work with lines and determine the slope of the lines informally and with the slope formula. Groups use their knowledge to calculate the slopes of parallel and perpendicular lines. They also...

Use a triangle area formula that works when the height is unknown. The eighth installment in a 16-part series on trigonometry revisits the trigonometric triangle area formula that previously was shown to work with the acute triangles....

Build on the understanding of finding angles using trigonometric ratios. Pupils develop the definitions of inverse trigonometric functions by restricting their domains in the 13th lesson of a 16-part series. They use inverse functional...

Explore angle relationships associated with transversals. Pupils construct parallel lines with a transversal and find the measures of the angles formed. They figure out how the different angles are related before constructing...

Your geometry learners will discover and show the construction of the circumcenter of a triangle. Guided by the steps in the activity, they construct perpendicular bisectors of each side that have a point of concurrency called the...

I like algebra, but graphing is where I draw the line! Worksheet includes three multiple-part questions on interpreting and drawing line graphs. It focuses on the abstract where neither axis has numbers written in, though both are...

This is a mid-module assessment for the 16th lesson in 29 geometry lessons. Individuals demonstrate their understanding of concepts such as vertical and adjacent angles, constructing geometric figures, and triangle congruence criteria.

Our teacher told us the formula had one-third, but why? Using manipulatives, classmates try to explain the volume formula for a pyramid. After constructing a cube with six congruent pyramids, pupils use scaling principles from...

Challenge your class to construct a definition for trapezoids. Looking at four examples and four non-examples, students individually create definitions and use them to classify an unknown shape. Allow for small group and whole-class...

Your learners find and construct the line of reflection between a triangle's pre-image and its reflection image in this short activity.

To take the longest path, go around—or was that go over? Class members measure scale drawings of a cylindrical vase to find the height and diameter. They calculate the actual height and circumference and determine which is larger.  

How do you show that something is a rectangle? This activity starts with four coordinate points and asks young geometers to explain whether they create a rectangle. Knowledge from both geometry and algebra come into play here, as well...

Use the given tasks and detailed teacher's commentary to introduce your 8th graders to the Pythagorean theorem and its converse. Embedded links to information about Egyptian geometry make your presentation interesting. Consider...