In a previous unit, students counted groups of up to 10 objects, recognized and wrote numbers 1–10, and connected numbers to quantities. In this lesson, students are introduced to addition as they count to find the total of 2 groups. Many students may approach these activities the same way that they answered “how many?” questions in previous units—by putting the 2 groups of objects together and then counting all of the objects. The Activity Syntheses focus on different strategies for finding the total number of objects given 2 groups of objects.

The addition language “add,” “adding,” and “put together” is used throughout the lesson. Students are not expected to produce this language until later in the unit. The notation “_____ and _____” is introduced by the teacher in Activity 2 as one way to represent combining the 2 groups. Students need time to see and hear teachers using this notation and other addition language before they can understand the more abstract language of “plus” or an expression “_____ + _____” which will be introduced in a later section. Putting together two groups of objects to determine the total prepares students for work in a future unit in which they will represent and solve Put Together, Total Unknown story problems.