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...

Without ever using the actual term, this exercise has the learner develop the key properties of the midsegment of a triangle. This task leads the class to discover a proof of similar triangles using the properties of parallel...

Young geometers become pool sharks in this analysis of the angles and lengths of a trick shot. By using angles of incidence and reflection to develop similar triangles, learners plan the exact placement of balls to make the shot....

One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles and...

This task asks learners to prove that the segment joining the midpoints of two sides of a parallelogram is both congruent and parallel to an adjacent side of the parallelogram. The activity would be good to use in a discussion about how...

The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...

Time doesn't fly when you're watching a snail cross a sidewalk. Combining the concepts of the Pythagorean Theorem and the distance, rate, and time formula, learners determine how long it takes a snail to go from one corner of a sidewalk...

Farming is full of mathematics, and it provides numerous real-world examples for young mathematicians to study. Here, we look at a cylinder-shaped storage silo that has one flat side. Given certain dimensions, students need to determine...

Your learners will make good use of the Socratic method in a collaborative task that begins with an assumed solution and ends with deeper understanding of the idea of determining two triangles congruent.

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...

This online exhibit from the American Antiquarian Society is filled with lithographs, catalogs, trade cards, and product labels that show how food production and distribution expanded in the last half of the 19th century. Be sure to...

Find guidelines to help you "solve" triangles, which means finding the value of missing sides and angles. Provided are examples of six scenarios in which you can solve a triangle's missing measurements, as well as relevant equations,...

This activity works with a PowerPoint presentation to have students answer questions as to what method a pair of triangles can be proven congruent: SSS, SAS, ASA, AAS, HL.

This interactive tool has student explore the topic of exterior angles of a polygon. The tool allows learners to change the number of sides to find the sum of the exterior angles of a variety of polygons.

In this activity, students will explore the concepts underlying the Triangle Inequality Theorem by comparing side lengths and angle measures of a triangle. They will use an interactive construction to see why this theorem is true.

In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...

As a resource for teachers, an activity of how to connect Venn Diagrams with the five methods of proving triangles congruent - SSS, SAS, ASA, AAS, HL - is explained.

The geometry tutorial investigates similar triangles. Students learn about the definitions and theorems of similar triangles. Topics included are angle-angle, side-side-side, and side-angle-side similarity. The activity has several...

The geometry tutorial investigates congruent triangles. Students learn about the definitions and theorems on congruent triangles. Some topics included are angle-side-angle, side-side-side, and side-angle-side congruence postulates. The...

Here is a site that clearly and thoroughly explains how to solve right triangles for any missing side or angle given any two pieces other sides or angles. There are example problems solved, problems for the student to attempt, and...

In Spanish. In this interactive activity you can understand and know how to apply direct and inverse homothety to simple shapes, apply Thale's theorem, construct similar polygons and work out their related measurements and know how to...