Lesson 3

The purpose of this lesson is for students to recognize that the number of objects in a group stays the same regardless of how they are counted.

In previous lessons, students counted groups of up to 20 objects and kept track of the objects that have been counted. In this lesson, students count the same collection as a partner, both to compare different ways of organizing and keeping track of collections of objects and to notice that the total number of objects stays the same. As students use and observe a variety of ways to count collections, they begin to understand that the order or arrangement that objects are counted in does not affect the number of objects. Students will further explore the conservation of number when a group of objects is rearranged in a future lesson.

• Create a pile of 18 connecting cubes to display.

• Each student needs a collection of 11–20 objects.

• Create a pile of 16 connecting cubes to display.

• Before playing, remove the cards that show numbers greater than 5.
  • Number Race, Stages 1 and 2
  • Subtraction Towers, Stage 1
  • 5-frames, Stages 1 and 2

What can the work of the second activity help you learn about your students’ understanding of counting and conservation of number?