This unit bundles student expectations that address representing and solving addition and subtraction problem situations by applying basic fact strategies and properties of

operations.

Prior to this unit, in Unit 02, students represented and solved contextual or real-world problem situations involving sums and minuends up to 10 while exploring basic fact

strategies and properties of operations.

During this unit, students extend representing and solving contextual or real-world problem situations involving sums and minuends up to 20 using spoken words, objects,

pictorial models, and number sentences. They explore and explain a variety of strategies to solve problems involving action (joining and separating problems), and problems

involving no action (part-part-whole and comparing problems). While demonstrating various strategies, students explore and apply properties of operations. Students are

expected to use a number sentence to represent the problem and explain that the equal sign represents a relationship where expressions on each side of the equal sign

represent the same value(s). Through the use of continued experiences with addition and subtraction situations, students begin to recognize basic fact relationships, which are essential for developing computational fluency. They also apply composition and decomposition of numbers to determine the unknown whole number when the unknown may be any one of the three of four terms in the equation. Within this unit, students also experience generating addition and subtraction situations when given a number sentence involving addition or subtraction of numbers within 20. Thorough understanding of analyzing problems and using the problem-solving process in addition and subtraction situations involving sums and minuends up to 20 is critical in setting the foundation for students’ success in mathematics as they progress through future grade levels.

After this unit, in Unit 10, students will revisit solving addition and subtraction problems using data found in picture and bar-type graphs.

Addition and Subtraction problems can be classified by the type of action or relationship described in the problems. This is a way to help students think about the action in the problem and understand the situation in context.

There are 2 big categories: Action and Relationships. Within Action type problems there are Joining and Separating problems. In these types of problems the result, change, or start could be the unknown. Within the Relationship category there are Part-Part-Whole and Comparing problems. When talking about Part-Part-Whole problems the whole or the part could be the unknown.

Helping students understand how to write an appropriate number sentence and understanding which part of the problem is unknown is key. Students must understand what they are solving.

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