Lesson objective: Understand that one way to perform addition is to add on to an already existing group to find the total amount.

Students bring prior knowledge of finding one more by counting on and adding by putting groups together from K.CC.4b and K.OA.1. This prior knowledge is extended to addition by adding to a group (within 5) as students begin to understand the operation of addition and recognize that it can be modeled in several ways. A conceptual challenge students may encounter is understanding that addition is not adding one more all of the time. We can add more than one to a group to get a total.

The concept is developed through work with a number path and mathematical vocabulary, which help students visually add to a group and express what the operation of addition means.

This work helps students deepen their understanding of operations because when students are able to connect counting to addition, they are able to understand how we can use mathematics strategically to manipulate numbers for a specific purpose.

Students engage in Mathematical Practice 4 (Model with mathematics) as they begin to explore how the operation of addition model real world situations using expressions and equations.

**Key vocabulary:**

- addition
- adding to
- begin
- greater/more
- total

**Special materials needed:**

- additional practice sheets
- manipulatives, if desired
- pencils/crayons