Making a Ten to Add and Subtract Unit of Study: Addition and Subtraction Strategies to 20 Global Concept Guide: 1 of 3

Content Development  This unit focuses on students being able to use efficient strategies to add and subtract numbers to 20.  The make a ten strategy is based on the concept of ten and the understanding that numbers from 11 to 20 can be expressed as ten and some more.  This process illustrates the use of the Associative Property of Addition. The fact is thought of as 8 + (2 + 5) then as (8 + 2) + 5.  A ten frame is the most effective model for helping children conceptualize the make a ten strategy.  By representing 8 in the ten frame, children can easily see that 2 more would make 10. Children can decompose 7 into This allows them to use to make a ten. Then they add the remaining 5 to find that = 15.

Day 1 Essential Question: How can you use the make a ten strategy to add?  Review all the ways to make ten-refer to anchor charts or other instructional materials used.  Go Math Lesson 3.8, p. 125 Listen and Draw should be put in a problem scenario, for example: Jaquan bought 9 red apples from the market. He then bought 6 yellow apples. How many apples does Jaquan have?  Observe student behavior as they use the ten-frame. Look to see which children move one yellow counter to fill the ten-frame. Can they explain that making a ten is easier to add because now I have ?  Students can work with small groups or partners to complete On Your Own, p. 127 and then move to Problem Solving, p Students who are proficient at making a ten may be able to complete Problem Solving on their own. By the end of Day 1, students will be able to model and make a ten to add.

Day 2 Essential Question: How can you decompose a number to help you add?  Start with the Dana Center, Session 13 Engage p and continue through the Develop pg Students will need a double tens-frame to model moving counters from one tens-frame to fill another tens- frame.Session 13  Follow up with Session 14/15 from the Develop section page for independent practice. Students roll number cubes to fill the two tens- frames and practice make a ten strategy.Session 14/15 By the end of Day 2, students will be able to make a ten to add. They will also be able to model the strategy on a double tens-frame. 9+4= 10+3=13

Content Development  Two different strategies will be explored in making a ten to subtract. The make a ten strategy requires students to use count up 1 or 2 more from 9 or 8 to make 10 and then subtract. Whereas, the break apart strategy (Associative Property of Addition) has students break apart the subtrahend into one part that is equal to the ones place of the teen number. 17 – 9 = ? I counted up one more to make ten. Then count up 7 more to make 17. So I counted up a total of 8. I have 17. I subtract 7 to get to 10. Next, break apart the 9 into a group of 7 and 2 more. Then I subtract the 2 more from the 10. I have 8.

Day 3 Essential Question: How can you make a ten to help you subtract?  Making a ten to subtract on Day 3 may be difficult if students do not have a conceptual understanding of decomposing and making a ten to add. This is critical in order for students to be successful.  Facilitate discussion about the relationship between addition and subtraction. Pose the question “what do you know about addition and subtraction?” Collect student responses and be sure to focus on the inverse relationship. If no student responds that they are inverse operations be sure to provide this language.  Go Math Lesson 4.4, p. 165 do the Listen and Draw whole group. Then provide partner practice with On Your Own p. 167 and work independently on Problem Solving p By the end of Day 3, students should be able to apply the make a ten strategy to subtract.

Day 4 Essential Question: How do you break apart a number to subtract?  Based on student needs, use Day 4 to continue modeling, problem solving and explaining the use of the strategy of breaking a part a teen number to subtract.  Go Math Lesson 4.5, p. 169 Listen and Draw focuses the students on decomposing 14 into a group of ten and 4 more. By decomposing into tens and ones students can more easily subtract. The second scenario has students use the remaining 10 to subtract 2 more leaving 8. How is this the same as 14 – 6 = (14 – 4) – 2  Provide ample exploration and discussion about the break apart strategy. Use pages for student/partner practice.  Problem Solving page 172 could be used for additional practice or independent informal progress check. By the end of Day 4, students will be able to break apart a teen number to subtract.

Day 5 Essential Question: How can I use different models and strategies to subtract?  Students will apply appropriate strategies to complete problem solving scenarios to subtract.  Go Math Lesson 4.6, p. 174 Try Another Problem can be used to launch problem solving. Be sure to have students focus on the question. Which strategy would be easiest to use for this situation? (Make a Ten)  Students can work with partners or independently on p. 175 – 176 to apply subtraction strategies in problem solving situations. The performance task will be administered in the second half of this day. By the end of Day 5, Students will be able to choose and apply efficient subtraction strategies.

Enrich/Reteach/Intervention Enrich  Go Math page 173B Enrich students write subtraction stories to match Fact Cards.  Go Math Enrich p. E34Enrich p. E34 Intervention/Small Group  Make 10 Dominoes Make 10 Dominoes  Go Math p. 169B Response to Intervention Tier 2  Go Math p. 171 Mathematical Practices in Your Classroom section.

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