This lesson is optional because it is an opportunity for extra practice that not all classes may need. In Activity 1, students learn Stage 2 of the How Are They the Same? center, which was first introduced in grade 1. In this new stage, called How Are They the Same?—Grade 2 Shapes, students develop their understanding of shapes by finding shared attributes. In Activity 2, students choose to continue working on How Are They the Same? or choose between two previously introduced centers that focus on shapes.