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 use to sort. Students determine the different ways their classmates sorted the shapes.

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

Reflect on the knowledge of two-dimensional shapes that students bring 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?