Slide 1 / 137 Slide 2 / 137 2nd Grade 2 Digit Addition and Subtraction 20151203 www.njctl.org Slide 3 / 137 Slide 4 / 137 Table of Contents Presentation 2 click on a topic to go to that section Standards for Mathematical s MP1 Make sense of problems and persevere in solving them. MP2 Reason abstractly and quantitatively. Mentally adding and subtracting 10 and 100 Addition Subtraction Mixed Addition and Subtraction Lab: Give and Take Slide 5 / 137 MP3 Construct viable arguments and critique the reasoning of others. MP4 Model with mathematics. MP5 Use appropriate tools strategically. MP6 Attend to precision. MP7 Look for and make use of structure. MP8 Look for and express regularity in repeated reasoning. Click on each standard to bring you to an example of how to meet this standard within the unit. Slide 6 / 137 Subtraction click on a topic to go to that section without 2 Digit without with Base Ten Blocks without Base Ten Blocks Subtraction with Subtraction 2Digit Subtraction Without Click to return to main Table of Contents Click to return to Subtraction Table of Contents
Slide 7 / 137 Slide 8 / 137 What number is shown? Now we want to subtract 14. When we subtract, we take away. ALWAYS start with the bigger number when you subtract. Slide 9 / 137 Just like when we added, you need to line up the two numbers. 2 7 1 4 Slide 10 / 137 Next, subtract the ones by crossing them out. 2 7 1 4 The ones are stacked and so are the tens. How many are left? Slide 11 / 137 Next, cross out the tens. Slide 12 / 137 2 7 1 4 3 2 7 1 4 1 3 How many are left?
Slide 13 / 137 What number is shown? Slide 14 / 137 Let's subtract 20 Our subtraction number model is: 32 20 = Slide 15 / 137 Rewriting it makes it easier to subtract. 3 2 2 0 Slide 16 / 137 What is the next step? 3 2 2 0 2 What do we subtract first? Slide 17 / 137 Slide 18 / 137 What do we do first? 3 2 2 0 1 2 85 62 If there is not a place value chart, it may help to draw a line between the tens and ones to keep them seperated.
Slide 19 / 137 Slide 20 / 137 Now what do we do? 85 62 3 What is the answer? 85 62 23 Slide 21 / 137 76 26 Slide 22 / 137 What should we do to this subtraction problem to make it easier to answer? 68 24 = Slide 23 / 137 Slide 24 / 137 Roll all 4 dice and then subtract the numbers. 68 24
Slide 25 / 137 1 If you take away 70, is the answer 24? Yes No Slide 26 / 137 2 If you take 12 away from this number, is the difference 7? Yes No Slide 27 / 137 3 Take away 83. What is the difference? Slide 28 / 137 4 Take 32 away from this number, what is the difference? Slide 29 / 137 Slide 30 / 137 5 What is the difference 67 47 =?
Slide 31 / 137 Slide 32 / 137 2 Digit Without Click to return to Table of Contents Slide 33 / 137 There are 24 children in a play. 11 children dance. The other children sing. How many children sing? Slide 34 / 137 There are 24 children in a play. 11 children dance. The other children sing. How many children sing? How many singers? 11 dancers 24 children in all 24 11 Slide 35 / 137 To find the difference, subtract: Remember: 1. Subtract the ones 2. Subtract the tens Slide 36 / 137 Number Model 24 11 = 13 or 24 11 13 Where is the bigger number in each problem?
Slide 37 / 137 There are 37 chairs at the play. There are 13 couches. How many more chairs than couches are there? How can we find the answer? Slide 38 / 137 Zachary sold 28 tickets for the play. Patrick sold 15 tickets. How many more tickets did Zachary sell than Patrick? Slide 39 / 137 On Friday, 49 people came to the play. On Saturday, 25 fewer people came. How many came on Saturday? Slide 40 / 137 6 There are 28 girls and 16 boys in the class. How many more girls than boys are in the class? A 12 B 14 C 36 D 46 Slide 41 / 137 Slide 42 / 137 7 Britney sold 39 boxes of popcorn and 18 sodas. How many more boxes of popcorn than sodas did she sell? 8 There are 34 geese and 24 ducks in a pond. How many more geese than ducks are there? A 11 B 18 C 21 D 26
Slide 43 / 137 9 There are 41 seagulls on the beach. Then 30 fly away. How many are left? Slide 44 / 137 10 Henry has 45 stamps. He gives 13 to Julie. How many stamps does he have left? Quiz Slide 45 / 137 Slide 46 / 137 Slide 47 / 137 Slide 48 / 137 What number is shown? with Base Ten Blocks Click to return to Subtraction Table of Contents
Slide 49 / 137 33 8 =? Now we want to subtract 8. What do we do first? 33 8 Slide 50 / 137 We have to take 8 ones away, but we do not have enough. How can we get more ones without changing the total number? Slide 51 / 137 33 8 = Now you can subtract!!! Cross out the ones that you take away. Slide 52 / 137 52 7 =? What do we need to do? What is the difference? Slide 53 / 137 Look at the problem below. Do you need to regroup? How do you know? 63 9 =? Slide 54 / 137 Look at the problem below. First, decide is you need to regroup. 41 5 =?
Slide 55 / 137 Look at the problem below. First, decide is you need to regroup. 83 2 =? Slide 56 / 137 Look at the problem below. First, decide is you need to regroup. 46 22 =? Slide 57 / 137 Look at the problem below. Draw base ten blocks to help you solve the problem. 35 7 =? Slide 58 / 137 Look at the problem below. Draw base ten blocks to help you solve the problem. 11 3 =? Slide 59 / 137 Slide 60 / 137 11 Which TWO problems require you to regroup? A 57 3 =? How will you know if you have to regroup? B 38 9 =? C 13 5 =? D 40 0 =?
12 Do you need to regroup? 45 8 =? Slide 61 / 137 13 Do you need to regroup? 67 8 =? Slide 62 / 137 Yes No Yes No Slide 63 / 137 Slide 64 / 137 14 15 56 8 Use base ten blocks at your seat to help you 93 14 Use base ten blocks at your seat to help you Slide 65 / 137 Slide 66 / 137
Slide 67 / 137 Slide 68 / 137 Look at the problem. What do we need to do first? without Base Ten Blocks 3 3 1 8 Click to return to Subtraction Table of Contents Slide 69 / 137 Before we subtract, we need to make sure the written problem matches the base ten blocks. 3 3 1 8 Slide 70 / 137 Before we subtract, we need to make sure the written problem matches the base ten blocks. 2 13 3 3 1 8 Slide 71 / 137 Start with the ones. Can we take 7 away from 2? What do we need to do? 5 2 3 7 Base Ten Blocks Slide 72 / 137 Let's! 6 9 5 7
Base Ten Blocks Slide 73 / 137 Let's! 70 35 = Slide 74 / 137 No Blocks! How can we solve this problem without base ten blocks? 5 2 3 6 Slide 75 / 137 No Blocks! Now let's subtract! Slide 76 / 137 4 12 5 2 3 6 6 0 2 7 Slide 77 / 137 9 4 7 8 Remember! More on top? No need to stop! More on the floor? Go next door! Slide 78 / 137 Numbers the same? Zeros the name! 25 12 81 61 74 36
Slide 79 / 137 Slide 80 / 137 Click on the picture below for more practice on the National Library of Virtual Manipulatives site. 16 85 37 48 Yes No Change the columns to 2 prior to starting Slide 81 / 137 Slide 82 / 137 17 94 25 = 71 Yes 18 67 58 No Slide 83 / 137 Slide 84 / 137 19 88 34 = 20 42 7 =
Slide 85 / 137 Slide 86 / 137 21 34 26 Slide 87 / 137 Slide 88 / 137 with Click to return to Subtraction Table of Contents Slide 89 / 137 Slide 90 / 137 There are 65 students on the playground. 47 are wearing sneakers. How many are not wearing sneakers? What do we have to do to find the answer? 6 5 4 7 Is there "more on the floor?"
Slide 91 / 137 Slide 92 / 137 5 15 6 5 4 7 We can not take 7 away from 5, so we have to regroup 1 ten as 10 ones. What do we do now? 5 15 6 5 4 7 8 What is the next step? Slide 93 / 137 One day 45 cars and 19 trucks were washed at the car wash. How many more cars than trucks were washed? Slide 94 / 137 How do I subtract? What do we have to do to find the answer? 4 5 1 9 Slide 95 / 137 Slide 96 / 137 There are 83 students eating lunch. 55 are eating hot lunch. How many students are not eating hot lunch? A soda cost 75 cents. Mr. West has 46 cents. How many more cents does he need for a soda?
Slide 97 / 137 22 There are 50 students in the library. 27 of them are wearing blue. How many are not wearing blue? A 33 Slide 98 / 137 23 Colin had 32 baseball cards. He sold 16. How many were left? B 37 C 23 D 77 Slide 99 / 137 24 Megan had 73 books at the yard sale. She sold 42. How many are left? Slide 100 / 137 25 The pet store has 58 fish. They sell 39 fish. How many fish are left at the pet store? A 31 B 115 C 211 D 35 Slide 101 / 137 Slide 102 / 137 26 In art class, Jeff made 61 paper moons. Kelly made 9. How many more moons did Jeff make?
Slide 103 / 137 Slide 104 / 137 Subtraction Click to return to Subtraction Table of Contents There are 84 apples on the apple tree. Sara picks 68 apples. How many apples are left on the tree? Slide 105 / 137 How can we write this problem to find the difference? Click each box to check your answer 84 68 Slide 106 / 137 Do we YES! have to regroup? There How is do more you on know? the floor. Regroup What do 1 we ten do for first? 10 ones Subtract the ones first, What do we do next? then the tens. Slide 107 / 137 Slide 108 / 137 Review NO! Do we have to regroup? Click each box to check your answer There How do is you more know? on top. 37 15 Subtract What do we the do ones. first? What Subtract do we the do next? tens.
Slide 109 / 137 Slide 110 / 137 Jenna picks up 34 sea shells. She puts 17 of them in a box. How many does she have left? Sadie buys 74 pieces of paper. She uses 44 for her book. How many pieces of paper are left? Slide 111 / 137 27 Mom bakes 23 cupcakes. She decorates 19 purple and the rest blue. How many were blue? A 16 B 4 C 14 D 34 Slide 112 / 137 28 Becky buys 57 apples and oranges. 23 are oranges. How many are apples? Pick the correct answer from each column to complete the subtraction sentence for this word problem. = 34 A 23 B 53 E 23 F 53 C 57 D 34 G 57 H 34 Slide 113 / 137 29 Kira can jump a rope 94 times. Myah can jump a rope 79 times. How many more times can Kira jump than Myah? Slide 114 / 137 30 The team scored 74 points. Shawn scored 36 of the points. How many points did the rest of the team score?
Slide 115 / 137 Slide 116 / 137 31 There are 49 markers in the box. 14 of them are being used. How many are left in the box? Quiz Slide 117 / 137 Slide 118 / 137 Mixed Click to return to main Table of Contents Slide 119 / 137 There are 78 people wearing blue hats and 35 people wearing red hats. How many hats in all? Is this Addition an addition or subtraction problem? The question asks How do we know? how many in all 78 +35 Slide 120 / 137 What do we add first? What Line do up we our have to do to numbers find the to answer? add
Slide 121 / 137 Slide 122 / 137 78 +35 8 + 5 = Now what do we do? 1 78 +35 3 Now what do we do? 1 + 7 + 3 = Slide 123 / 137 1 78 +35 3 Slide 124 / 137 1 78 +35 113 Slide 125 / 137 The paint store has 64 cans of paint. They sell 55 cans. How many cans are left? The problem talks about taking How do we know? away and asks how many are left. Is this an addition or subtraction Subtraction problem? Slide 126 / 137 64 55 Click each box to check the answer Line What up do the we numbers, have to with do to the find biggest the answer? number on top to subtract.
Slide 127 / 137 35 + 58 Slide 128 / 137 There are 50 blue birds and 86 red birds. How many birds are there all together? What clue words tell us what kind of problem this is? Slide 129 / 137 Two boys collected a total of 43 rocks. If John collected 22, how many did Dave collect? Slide 130 / 137 32 Kurt has 70 pennies. He gives Jay 48 pennies. How many pennies does he have left? A 38 B 22 C 118 D 32 Slide 131 / 137 33 Jenny does 29 jumping jacks. Nicole does 33 jumping jacks. How many jumping jacks did they do all together? Slide 132 / 137 34 There are 56 yellow flowers and 53 red flowers. How many flowers in all? A 52 B 16 C 62 D 4
Slide 133 / 137 35 There are 38 kids that have brown eyes and 27 kids that have blue eyes. How many more kids have brown eyes? Slide 134 / 137 36 Jack has to drive 82 miles. He already drove 47 miles. How many more miles does Jack have to drive? Slide 135 / 137 Slide 136 / 137 Lab: Give and Take regrouping/ trading tens and ones while playing this game Click here for complete directions Click to return to main Table of Contents Slide 137 / 137