This Fluency Activity is a part of the Lesson 5, Unit 2, Grade K. With the teacher hiding the shapes, students get accustomed to visualizing, a skill they will be applying to numbers, for example, with dot cards. This is an imperative step in developing number sense. It is a significant moment when students realize they can make a mental picture of something. One shape at a time, show students each shape briefly. Then, take the shape out of view.