Slide 1 / 188 Slide 2 / 188 First Grade Subtraction to 20 Part 1 2015-11-23 www.njctl.org Slide 3 / 188 Slide 4 / 188 click on the topic to go click on the topic to go to that section to that section Table of Contents Pt. 1 Table of Contents Pt. 2 - Real World Subtraction with Manipulatives - Patterns when Subtracting 10 - Subtraction Sentences - Lab - Zero Wins - Number Stories - Fact Families - Comparing Groups - Lab - Fact Family Domino Grab - Subtraction on a Number Line - Fact Triangles - Subtraction on a Number Grid - Lab - Math Action Goes Both Ways - Subtracting Zero - Missing Number - Subtracting All - Missing Number Part 2 - Subtracting 1, 2, 3 - Get to Ten - Subtracting Ten - Get to Ten Part 2 Slide 5 / 188 Slide 6 / 188 Standards for Mathematical Practices MP1 Make sense of problems and persevere in solving them. MP2 Reason abstractly and quantitatively. MP3 Construct viable arguments and critique the reasoning of others. Real World Subtraction MP4 Model with mathematics. with Manipulatives 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 Click to return to you to an example of how to meet Table of Contents this standard within the unit.
Slide 7 / 188 Slide 8 / 188 When we subtract, we break a whole How many turkeys are left? into 2 smaller parts. 4 Four turkeys are on the fence. Whole Teacher Notes Two fly away. 2 (Flew away) (Left) How many turkeys left? Part Part part 7 baseballs in the whole group part Slide 9 / 188 Slide 10 / 188 How many potatoes are left? How many dogs are left? Jen has six potatoes on her plate. Three potatoes roll off. There are 5 dogs in the park. Teacher Notes Whole How many potatoes are left? 3 dogs ran away. Teacher Notes 6 How many dogs are left? Whole Part Part 3 (Left) (Rolled away) Part Part We could also ask, "What is the difference in the number of potatoes we started with, and the number of potatoes left?" Slide 11 / 188 Slide 12 / 188 Using Counters Let's Show it With Counters We can use counters to help us solve subtraction problems. 8 2 ______ 5 3 ________ apple pies pies are eaten pies left dogs ran away dogs left
Slide 13 / 188 Slide 14 / 188 Let's Practice Let's Practice 10 5 3 3 ______ ______ balloons blow away leaves on a tree leaves fall off balloons are left leaves left Slide 15 / 188 Slide 16 / 188 Let's Practice Let's Practice _____ left 6 take away 1 8 take away 3 _____ left Slide 17 / 188 Slide 18 / 188 Connecting Cubes Let's Practice We can also use connecting cubes to help us subtract. Each cube represents an object. To show subtraction, remove the amount taken away. 9 take away 5 _____ left 2 1 ________ blue birds flies away birds left
Slide 19 / 188 Slide 20 / 188 Let's Practice 1 7 dogs are outside and 3 run away. There are 10 dogs in all. Yes 5 apples 3 are rotten _____ apples left No 7 rakes 2 break _____ rakes left Slide 21 / 188 Slide 22 / 188 2 3 cats and 3 run away. _____ cats left 3 4 rakes and 2 break. _____ rakes left A 5 A 2 B 6 B 6 C 0 C 8 Slide 23 / 188 Slide 24 / 188 4 3 pumpkins and 2 roll away. 5 8 hats and 3 blow away. _____ hats left ____ pumpkins left
Slide 25 / 188 Slide 26 / 188 Slide 27 / 188 Slide 28 / 188 Subtraction Sentences 8 minus 2 equals 6 Subtraction Sentences x x 1 2 3 4 5 6 Click to return to Table of Contents Slide 29 / 188 Slide 30 / 188 Subtraction Sentence Parts The Minus Sign - A subtraction sentence has 2 parts, a minus The minus sign means to take away. sign, an equal sign and a whole. Minus Sign Equal Sign 8 - 2 = 6 Whole Parts
Slide 31 / 188 Slide 32 / 188 Subtraction Sentence Parts Subtraction Sentence Parts Slide the labels to the correct part of the Slide the labels to the correct part of the subtraction sentence. subtraction sentence. Minus Sign Minus Sign Equal Sign Equal Sign 3 - 1 = 2 9 - 4 = 5 Whole Whole Parts Parts Slide 33 / 188 Slide 34 / 188 The Minuend The Subtrahend The first number is the largest number. The second number tell us how many we are taking It is called the minuend. away. This is called the subtrahend. 8 - 6 = 2 8 - 6 = 2 Minuend Subtrahend Slide 35 / 188 Slide 36 / 188 Left or Right The Difference Subtraction sentences can be written with the difference on the left or right of the equal sign. The answer is called the difference. 11 - 7 = 4 Will the difference be greater or less than the minuend? 8 - 6 = 2 Difference 4 = 11 - 7 Difference Difference
Slide 37 / 188 Slide 38 / 188 Top to Bottom See, Write and Say Subtraction sentences can also be written top to bottom. x See x x 11 - 7 = 4 Write 4 - 3 = 1 11 - 7 Say 4 4 minus 3 equals 1 Difference Slide 39 / 188 Slide 40 / 188 9 1 3 - 2 = 1 3 2 1 - 5 2 4 3 Slide 41 / 188 Slide 42 / 188 2 1 6 - 1 = 5 - 2 3 2 1 2 0 3
Slide 43 / 188 Slide 44 / 188 8 1 9 - 3 = 6 - 2 2 3 1 2 6 3 Slide 45 / 188 Slide 46 / 188 6 Which subtraction sentence matches this story? Six kids are playing. Four kids go home. Now there are two kids left. A 6 -2 = 4 B 6 - 4 = 10 C 6 - 4 = 2 Slide 47 / 188 Slide 48 / 188 7 Which subtraction sentence matches this 8 Which subtraction sentence matches this story? story? Five pumpkins are on the table. Six balloons are tied on the fence. The farmer sells two. Five pop. There are three pumpkins left. 1 balloon is left. A 6 - 5 = 1 A 5 - 3 = 2 B 6 - 1 = 5 B 5 - 2 = 3 C 6 - 5 = 2 C 5 - 2 = 7
Slide 49 / 188 Slide 50 / 188 9 Which subtraction sentence matches this 10 Which subtraction sentence matches this story? story? Ten chickens are at the farm. Thirteen pieces of candy are on the table. Four fly away. Jen eats 5 pieces. How many chickens are left? There are 8 pieces left. A 10 - 6 = 4 A 13 - 8 = 5 B 10 - 4 = 6 B 13 - 5 = 7 C 10 - 4 = 5 C 13 - 5 = 8 Slide 51 / 188 Slide 52 / 188 Slide 53 / 188 Slide 54 / 188 Word Problems When looking at a subtraction word problem, we Number Stories need to figure out if the numbers we know show the whole number of things or the parts. Click to return to Table of Contents
Slide 55 / 188 Slide 56 / 188 Story 2: Cats Story 1: Pennies There are 5 cats on the fence. Jim has 8 pennies. 1 jumps down. His mom takes 2 away. How many cats are left on the fence? How many pennies does Jim have left? - = - = Underline what we know. Underline what we know. Circle what we want to Circle what we want to know. know. Slide 57 / 188 Slide 58 / 188 Story 3: People Let's Make up a Story There are 4 people at the farm. 2 people leave the farm. How many people are left at the farm? Make up a story for this number sentence. - = 10 - 7 = Underline what we know. Circle what we want to know. Slide 59 / 188 Slide 60 / 188 Let's Make up a Story Class Activity Make up a story for this number sentence. 6 Student made subtraction stories - 3
Slide 61 / 188 Slide 62 / 188 11 There are 8 ants on a log. 12 There are 8 ducks in the pond. 3 crawl off. 3 swim away. How many ants are left on the log? How many ducks are left in the pond? A 4 B 5 C 6 Slide 63 / 188 Slide 64 / 188 13 You have 12 pencils on your box. 14 There are 9 hippos in a pond. 6 of the pencils break. 5 of them get out. How many pencils are left in all? How many hippos are still in the pond? A 4 B 5 C 6 Slide 65 / 188 Slide 66 / 188 15 You see 11 cookies in a box. Nine of them are chocolate chip. How many are not chocolate chip? A 4 B 2 C 3
Slide 67 / 188 Slide 68 / 188 Comparing Groups Click to return to Table of Contents Slide 69 / 188 Slide 70 / 188 Comparing Comparing You can subtract to compare groups How many cubes are in each train? 6 ______ 4 ______ Which number is more? Circle it Slide 71 / 188 Slide 72 / 188 Comparing Comparing Words We know that there are more blue blocks than green blocks. If we want to know how many more blue blocks we can subtract. 6 How much less? How much more? How much shorter? How much taller? 4 How many fewer? How many more? How much smaller? How much larger? ______ - ______ = ______ How much further? How much closer? The bigger number is written first and then subtract the smaller number.
Slide 73 / 188 Slide 74 / 188 Comparing Comparing ______ ______ ______ ______ ______ - ______ = ______ ______ - ______ = ______ The bigger number is written first and then subtract the The bigger number is written first and then subtract the smaller number. smaller number. Slide 75 / 188 Slide 76 / 188 Monkeys and Zebras There are 8 monkeys at the zoo. There are 12 zebras at the zoo. How many more monkeys than zebras? ______ - ______ = ______ Slide 77 / 188 Slide 78 / 188 Using Circles Using Circles If you do not have cubes or pictures, draw circles to help. If you do not have cubes or pictures, draw circles to help. There are 6 elephants. There are 10 tigers. There are 2 lions. There are 6 cheetahs. How many fewer lions? How many more tigers? Draw a line to Draw a line to E see what is see what is left behind. left behind. L ______ - ______ = ______ ______ - ______ = ______
Recommend
More recommend
