Lesson objective: Sort and classify objects using defining and non-defining attributes; identify and name sorting rules.

This lesson helps to extend understanding of attributes. Students will sort and classify objects using non-defining attributes such as color, shape, and size of an object and defining attributes such as number of sides and corners. Students will describe in their own words the sorting rule and provide mutliple examples to support their thinking.

Students engage in Mathematical Practice 3 as they construct viable arguments and critique the reasoning of others. Students will use clear definitions with peers as they define attributes and provide a viable argument reasoning why a shape lacks specific attributes. Students also engage in Mathematical Practice 7 as they look for and make use of structure. Students will use the patterns seen in different shapes to make comparisons. Students will use the relationships demonstrated in the defining attributes to explain similarities and differences.

**Key vocabulary:**

- attribute
- defining
- non-defining