Lesson objective: Understand that shapes have attributes that can be identified.

Students bring prior knowledge of attributes from 2.G.A. This prior knowledge is extended to comparing figures as students identify similar and different attibutes among shapes. A conceptual challenge students may encounter is distinguishing which are the defining attributes,

The concept is developed through work with plane figures, which illustrate the attributes.

This work helps students deepen their understanding of equivalence because identifying similar or different characteristics helps students recognize equivalence.

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. Students also engage in Mathematical Practice 1 (make sense of problems and persevere in solving them) as they make conjectures involving attributes and measures of shapes and analyze various ways of approaching problems.

**Key vocabulary:**

- attribute
- rectangle
- quadrilateral
- rhombus
- square
- polygon