In this unit, students use the strategies they have learned for composing and decomposing numbers to solve addition and subtraction problems. Students will also learn that different strategies will lead to the same solution. A conceptual challenge students may encounter is interpreting addition and subtraction in more than one way. Students should also understand that sums and differences stay the same regardless of the strategy used.
Key Concepts:
 The meaning of addition does not change when different strategies are used.
 The meaning of subtraction does not change when different strategies are used.
 Fluently adding and subtracting can help us solve math problems more efficiently.
Prior Knowledge Needed:
 Understand addition as putting together and adding to, and understand subtraction as taking apart and taking from; (Grade K, Unit 10 K, K.OA.A.1)
Units on the Horizon:
 Understand ten ones make a ten (Grade 1, Unit 1)
 Using data to add and subtract within 20 (Grade 1, Unit 2)
 Developing addition and subtraction strategies (Grade 1, Unit 6)
Lessons

Lesson objective: Understand that the meaning of addition does not change when different strategies are used. Students bring prior knowledge of understanding addition as putting together and adding to from K.OA.A.1. This prior knowledge is extended to u...

Lesson objective: Add numbers using number bonds and counters. This lesson helps to build procedural skills in whole number addition. Number bonds and counters are used here because they highlight the put together strategy for addition. This work develo...

Lesson objective: Add by composing and decomposing 10. This lesson helps to build procedural skill with composing and decomposing 10. An arithmetic rack is used here because it highlights the total 10, both visually and kinesthetically. This work develo...

Lesson objective: Apply concepts of addition by solving problems involving addition with more than one strategy. This lesson provides an opportunity for students to apply their knowledge and understanding of additon strategies to a reallife situation. ...

Lesson objective: Understand that using different strategies to subtract will result in the same difference. Students bring prior knowledge of subtraction strategies from understanding addition as putting together and adding to and understanding subtrac...

Lesson objective: Subtract using different strategies. This lesson helps to build procedural skill with subtraction. Connecting cubes are used here because they support the students by serving as a concrete representation of subtraction as taking away a...

Lesson objective: Apply subtraction strategies to solve realworld problems. This lesson provides an opportunity for students to apply their knowledge and understanding of subtraction strategies to a reallife situation. Students are asked to find out h...

Lesson objective: Understand that fluency with numbers helps us to solve equations more efficiently. Students bring prior knowledge of understanding addition as putting together and adding to and subtraction as taking apart and taking from (Grade K, Uni...

Lesson objective: Fluently add and subtract within five. This lesson helps to build fluency with addition and subtraction within five. A game is used here because it supports quick recognition of addition and subtraction facts. This work develops studen...

Lesson objective: Apply fluency skills in order to solve problems more efficiently. This lesson provides an opportunity for students to apply their knowledge and understanding of fluency within five to a reallife situation. Students are asked to solve ...