1. Model and Draw Subtraction with 3-digit Numbers Unit of Study 6: 3-digit Addition and Subtraction Global Concept Guide: 2 of 4

2. Content Development  The purpose of this GCG is to focus on the place value strategy.  When breaking apart 3-digit numbers, students should build upon their understanding of this strategy with 2-digit numbers.  Throughout this GCG students should be able to decompose 3-digit numbers in different/efficient ways in order to subtract through the use of real-world problem solving scenarios.

3. Day 1  Essential question: How can I use a number line to subtract 3-digit numbers?  Students will focus on putting numbers into expanded form to subtract on a number line.  Number line Learn Zillion video~ Quick code ~ LZ2978Learn Zillion  Sample engage question:  A killer whale at birth weighs 181 kilograms. An Asian elephant weights 117 kilograms. How much more does the killer whale weigh than the Asian elephant at birth?  Students should be breaking apart numbers efficiently to solve on a number line. Additional subtraction problems.subtraction problems. By the end of Day 1, students will be able to subtract 3-digit numbers on a number line. Possible daily journal questions.journal questions.

4. Day 2  Essential question: How can I model 3-digit subtraction?  Today students should model 3-digit subtraction using base-ten blocks and their place value mat. Make sure to use vocabulary like regroup, trade, and exchange. Students should recognize that when they make a trade, the value doesn’t change.  Sample engage question:  There were 403 coins in Linda’s piggy bank. Three hundred fifty-seven of the coins were dimes. How many of the coins were not dimes? (You must be logged in As a teacher in order To view this video on YouTube)  Additional problems that can be used. Additional problems  By the end of Day 2, students will be able to model 3-digit subtraction. Possible daily journal questions.daily journal questions ClickClick to view a demonstration of modeling of 3-digit subtraction.

5. Day 3  Essential question: How can I connect my models of 3-digit subtraction to drawings?  Students should still build models but connect to a quick picture.  Sample engage question:  A baby beluga whale weighs 162 lbs. and a baby hippopotamus weighs 126 lbs. How much more does the baby beluga whale weigh than the baby hippopotamus? (You must be logged in As a teacher in order To view this video on YouTube)  Additional problems that can be used. Additional problems  By the end of Day 3, students will be able to connect their model of 3-digit subtraction their quick picture. Possible daily journal questions.daily journal questions ClickClick to view a demonstration of connecting a 3- digit subtraction to drawings.

6. Day 4  Essential question: How can I regroup when there are zeroes in the number you are subtracting from?  Students should be building this with base-ten blocks.  Sample engage question:  Zero the Hero visited Lowry Park Zoo. There are 200 seats at the bird show. If 149 people are already seated, how many seats are left? (You must be logged in as a teacher to view YouTube.)  Additional problems that can be used. Additional problems  By the end of Day 4, students will be able to regroup when there are zeroes in the number they start with. Possible daily journal questions.daily journal questions ClickClick to view a demonstration of regrouping when there are zeroes in the number you are subtracting from.

7. Day 5  Essential question: How can I record my steps when subtracting 3- digit numbers?  Mrs. Prong had 300 green folders and 149 red folders. How many more green folders than red folders did Mrs. Prong have? (You must be logged in as a teacher to view YouTube.)  Additional problems you can use. Additional problems  By the end of Day 5, students will be able to record their steps when subtracting 3-digit numbers. Possible daily journal questions.daily journal questions ClickClick to view a demonstration of recording the steps when subtracting 3-digit numbers.

8. Enrich/Reteach/Intervention Reteach  Students needing more time should focus on modeling and understanding flexibility of numbers. THEY SHOULD NOT BE REQUIRED TO USE THE STANDARD (TRADITIONAL) ALGORITHM!  Videos could be used for reteach as well. (You must be logged in as a teacher to view YouTube.) Enrich  Enrich TE Pp.305B  Enrich TE p. 313B ClickClick to view a demonstration of recording a model of 3- digit subtraction. ClickClick to view a demonstration of regrouping when there are zeroes in the number you are subtracting from.