Lesson objective: Identify attributes of quadrilaterals, and use them to compare shapes.

This lesson helps to build fluency with recognizing attributes of shapes. Two dimensional figures are used here because they clearly illustrate the attributes. This work develops students' understanding that all rhombuses, rectangles and squares are examples of quadrilaterals, but not all quadrilaterals fit in those subcategories.

Students engage in Mathematical Practice 7 (look for and make use of structure) as they determine categories and subcategories of shapes by identifying and reasoning about their attributes.

**Key vocabulary:**

- quadrilateral
- trapezoid
- rectangle
- rhombus

**Special materials needed:**

- index card for each student, or other tool for measuring square corners.