Lesson objective: Understand that shapes in different categories may share attributes, and that shared attributes can define larger categories.

This lesson helps to build fluency with recognizing attributes of shapes. Polygons are used here because they illustrate the attributes of shapes. This work develops students' understanding that shapes in different categories (rhombuses, rectangles, etc.) may share attributes.

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:**

- attribute
- side
- square corner
- pentagon
- triangle
- quadrilateral

**Special materials needed:**

- index card for in class practice