1. Ways to make 20 Unit of Study: More Addition & Subtraction Strategies Global Concept Guide: 3 of 3

2. Content Development  It is important to help children understand that fluency means to be able to recall a fact quickly without having to count or to use other less efficient strategies.  Remember: we want children to understand the concept of addition and subtraction, then develop strategies to add and subtract, and finally develop fluency with the facts.  Since we are currently building a foundation for later work with all numbers and operations, students should make the connection that they can use the same strategies for the basic facts to 10 to work out facts to 20 and then with greater numbers in the future.  Sometimes students may be confused about how addition and subtraction facts can have the same sum or difference when they are not related.  Example: 2 + 4 = 6 and 8 – 2 = 6, they are both ways to make 6 but the sentences are not related, the parts of the whole are different.

3. Day 1  Build Conceptual Knowledge: Go Math Lesson 5.8 Algebra – Ways to Make Numbers to 20  Students will use 3 different colors of snap cubes to model different ways to make numbers between 10 – 20.  Connect back to strategies learned when making 10.  Discuss how students may have different ways to make the same number and have them justify their answers.

4. Day 2  Building Conceptual Knowledge: Go Math Lesson 5.10 Basic Facts to 20  Students will be building their fluency by practicing the strategies they’ve learned.  Have students explain why they chose a particular strategy and to describe what happens to the numbers when that strategy is used.  Connect to Go Math Lesson 5.4 Use Addition to Check Subtraction  Using the problems from Lesson 5.10, model connections to using addition to check subtraction.  It is not necessary to have students do the problems in Lesson 5.4 if they are showing this strategy while completing problems in Lesson 5.10.

5. Day 2 Focus on these ideas when modeling to develop students’ understanding of the thought process they are using when adding to check subtraction.

6. Enrich/Reteach/Intervention  Reteach/Intervention  Go Math Chapter 5: TE p. 213B Tier 2 Intervention  Go Math Chapter 5: R43  Go Math Chapter 5: TE p. 221B Tier 1 Intervention  Enrich  Go Math Chapter 5: TE p. 213B Enrich  Go Math Chapter 5: TE p. 221B Enrich