Lesson 3

The purpose of this lesson is for students to describe two-dimensional shapes using their own language, sort them, and explain how they sorted.

In kindergarten, students named and described squares, rectangles, triangles, and circles, and the shapes represented by pattern blocks. In prior lessons, students used the names of two-dimensional shapes when describing three-dimensional shapes.

In this lesson, students use their understanding of two-dimensional shapes to sort them. Students may choose to sort according to defining attributes or not. What is most important is that students can name the categories they used to sort. Students look at different ways their classmates sorted the shapes and determine how they sorted. 

The shape cards used in this lesson will be used again throughout the section.

• Create a set of Flat Shape Cards from the blackline master for each group of 2. 

• Display each group's work from the previous activity. 

Reflect on the knowledge of two-dimensional shapes students are bringing with them from kindergarten. What unfinished learning or misunderstandings do your students have about shapes? How did you leverage those misconceptions in a positive way to further the understanding of the class?