## Lesson: Triangles and Quadrilaterals

Developing the Concept

Students have learned about triangles and quadrilaterals and their properties. Now they will apply these properties to solve some problems.

**Materials:** pencil, protractor, ruler, and several sheets of paper for each student

**Preparation:** Display the five sheets showing the five types of quadrilaterals and their properties created in the "Introducing the Concept" section.

**Wrap-Up and Assessment Hints**

Asking students to construct polygons with various properties is a good way to see if they understand the concepts. For example, students should be able to tell you that you can't have an equilateral triangle with a right angle because all the angles in an equilateral triangle measure 60 degrees. Similarly, if you ask students to draw a rhombus that is not a square, they should be able to explain that the figure would have all four sides congruent but it would have no right angles.