How can opposites be equal? Pupils learn about the measures of angles when two lines intersect by watching an educational video. They see how vertical angles are congruent, and solve problems using this idea.

Properties spawn from parallel sides. With the aid of diagrams, the presentation shows the different properties of parallelograms. The segment of an extensive geometry playlist lists the properties that using the parallel sides of a...

If it has the properties of a parallelogram, it must be a parallelogram. A segment of a playlist on geometry presents the converses of the properties of a parallelogram. Given a quadrilateral with specific characteristics, the video...

Introduce the class to the quad in quadrilaterals. The presentation provides the names and definitions for the basic special quadrilaterals. A graphic shows the connections between the types of quadrilaterals introduced. The video points...

What does it mean for a quadrilateral to be cyclic? Mathematicians first learn what it means for a quadrilateral to be cyclic. They then investigate angle measures and area in such a quadrilateral.

A motivating activity is coupled with the use of algebra to explore the process for identifying the value of an angle. Somehow, it feels like a bit like magic when Sal shows the solution for the final problem. Also, it would be...

While exploring the concept of transversals, Sal discusses corresponding angles, congruent angles, and opposite/vertical angles. He provides a thorough summation of these mathematical concepts. It is the first installment in a series...

In this second video in the series on angles, students explore the concept of supplementary and complementary angles. In addition, intersecting lines and opposite angles are explained.

A rectangle, a rhombus, a square, a trapezoid - are any of these a parallelogram? What are the criteria that make a shape a parallelogram? It has something to do with parallel sides, congruent sides, and congruent angles. Help your young...

A motivating activity is coupled with the use of algebra to explore the process for identifying the value of an angle. Somehow, it feels like a bit like magic when Sal shows the solution for the final problem. Also, it would be...

While exploring the concept of transversals, Sal discusses corresponding angles, congruent angles, and opposite/vertical angles. He provides a thorough summation of these mathematical concepts. It is the first installment in a series...

Learners address 14 questions that include naming all pairs of opposite and supplementary angles for sets of intersecting lines and then, finding the measure of the unknown angle. They determine the measure of the angle that is...

In this identifying alternate interior and exterior angles instructional activity, students study two diagrams and complete a T-Chart by placing angle pairs in the correct columns. Students fill in six blanks.

In this squares and rhombi activity, 10th graders solve 8 different problems with quadrilaterals, especially the square and rhombus. First, they use the given rhombus and the given information to find the value for each statement. Then,...