1. Mathematics Chapter 1: Addition & Subtraction with regrouping Grassy Lake Elementary School Third Grade Created by: Mrs. Tamara Russell

2. Goals To identify and write related addition and subtraction facts. To solve number sentences for missing addends. To add 2-digit numbers without regrouping. To subtract 2-digit numbers without regrouping. To use the problem solving skill choose the operation.

3. Materials Scrap paper or white boards Pencils or expo markers Erasers or paper towels for the boards

4. Today’s Lesson By the end of today’s lesson, you will be able to add and subtract two digit numbers using regrouping. 56 +15 71 62 - 15 47 151

5. Lesson Did you know that every number has a home, just like you? We call those numbers homes their place value. In order to add or subtract two digit numbers we need to review place value! Let’s go!

6. Let’s do some problems! You will need a white board, a marker and an eraser. Together we will do six problems – three addition and three subtraction. When we are all done, we should know how to add and subtract by regrouping! Let’s do it!

7. Two digit addition Always remember to line up your numbers properly. Start at the right. (6 + 5) Put the sum of 6 + 5 in its house. (11) Oops! Too many! Carry a number! Now, add the numbers in the tens’ column. (5 + 1 + 1) Put the sum of 5 + 1 + 1 in the tens’ column. (7) 5 6 + 1 5 TensOnes 17 1

8. Again? Always remember to line up your numbers properly. Start at the right. (4 + 6) Put the sum of 4 + 6 in its house. (10) Oops! Too many! Carry a number! Now, add the numbers in the tens’ column. (2 + 3 + 1) Put the sum of 2 + 3 + 1 in the tens’ column. (6) 6 4 + 3 2 TensOnes 06 1

9. Last time? Always remember to line up your numbers properly. Start at the right. (2 + 9) Put the sum of 2 + 9 in its house. (11) Oops! Too many! Carry a number! Now, add the numbers in the tens’ column. (3 + 1 + 1) Put the sum of 3 + 1 + 1 in the tens’ column. (5) 9 2 + 1 3 TensOnes 15 1

10. Let’s subtract! Always remember to line up your numbers properly. Start at the right. (3 - 4) Oops! You can’t subtract 4 from 3! Time to borrow! Borrow ten from next door and make 13. And subtract a ten to make 6. Now, subtract. (13 – 4) Put your answer in the ones place. Last, subtract 6 – 3. Put your answer in the tens place! 4 3 - 3 7 TensOnes 93 13 6

11. Again? Always remember to line up your numbers properly. Start at the right. (2 - 4) Oops! You can’t subtract 4 from 2! Time to borrow! Borrow ten from next door and make 12. And subtract a ten to make 6. Now, subtract. (12 – 4) Put your answer in the ones place. Last, subtract 3 – 2. Put your answer in the tens place! 4 2 - 2 4 TensOnes 81 123

12. Last time! Always remember to line up your numbers properly. Start at the right. (5 - 9) Oops! You can’t subtract 5 from 9! Time to borrow! Borrow ten from next door and make 15. And subtract a ten to make 7. Now, subtract. (15 – 9) Put your answer in the ones place. Last, subtract 7 – 7. The answer is zero and does not change the amount in the number, so you don’t have to put it there! 9 5 - 7 8 TensOnes 6 157

13. Independent work Complete these practice problems on your white board. Raise your hand when you are done so that I can check your work! You have ten minutes to work and then I’ll show you the answers. 24 64 + 16- 58 23 78 + 48- 59 40 1 71 1 6 514 19 618

14. Fantastic! How did I get such smart cookies? Tomorrow’s Lesson: Working on addition and subtraction story problems