In this unit students focus their understanding on the structure of addition. Throughout the unit students engage in tasks that necessitate making use of the commutative and associative properties in problem solving and applying these properties to calculations. While students are not expected to use the formal terminology for the commutative and associative properties, they will continue to build understanding of the commutative property while also exploring the associative property of addition. The tasks in this unit introduce students to using the associative property as a strategy to add more than two addends.
Content Standards: 1.OA.A.2 and 1.OA.B.3
Practice Standards: S.MP.1, S.MP.2, S.MP.7, S.MP.8
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Unit at a Glance
Lessons 13 (3 days)
Key Concept 1: We can add more than two numbers together.

Lesson objective: Understand that we can add more than two numbers. Students bring prior knowledge of solving addition and subtraction word problems within 10 (K.OA.A.2). This prior knowledge is extended to solving problems that involve three addends wh...

Lesson objective: Find three addends that equal the given sum. This lesson helps to build fluency with addition of three addends. Connecting cubes are used here because they support decomposing and composing numbers. A number line is also used to help s...

Lesson objective: Apply the knowledge of addition with three addends. This lesson provides an opportunity for students to apply their knowledge and understanding of solving problems that involve addition of three addends to a realworld situation. Stude...
Lessons 46 (3 days)
Key Concept 2: When we are adding numbers together, it doesn't matter in what order they are written.

Lesson objective: Understand the commutative property of addition with three addends. Students bring prior knowledge of the commutative property of addition from 1.OA.B.3. This prior knowledge is extended to three addends. A conceptual challenge student...

Lesson objective: Prove that changing the order of the addends does not change the sum. This lesson helps to build fluency with adding three numbers in any order. A number line is used here because it supports the understanding that adding numbers in an...

Lesson objective: This lesson provides an opportunity for students to apply their knowledge and understanding of addition of three addends in any order to a reallife situation. Students are asked to make a plan and two possible schedules for spending t...
Lessons 710 (4 days)
Key Concept 3: When we are adding numbers together, it doesn't matter how they are grouped.

Lesson objective: Understand that we can group addends by known facts to solve problems more efficiently. Students bring prior knowledge of making a ten from K.OA.A.4. This prior knowledge is extended to adding three numbers as students group them by kn...

Lesson objective: Add three addends by grouping known facts such as tens or doubles to help solve problems more efficiently. This lesson helps to build fluency with addition of three addends. A ten frame is used here because it supports the concept of m...

Lesson objective: Solve word problems that involve the addition of three addends by grouping known facts such as tens or doubles to help solve problems more efficiently. This lesson helps to build fluency with addition of three addends. A ten frame is u...

Lesson objective: Apply knowledge of the commutative and associative properties to find the sum of three addends in different ways. This lesson provides an opportunity for students to apply their knowledge and understanding of grouping addends by known ...