Slide 1 / 234 Slide 2 / 234 3rd Grade Multiplication 2015-12-30 www.njctl.org Slide 3 / 234 Slide 4 / 234 Table of Contents Relate addition to multiplication click on the topic to go Arrays to that section Multiply by 1 and 0 Multiply by 2 Multiply by 5 Multiply by 10 Relate Multiplication to Addition Multiplication Table Activity Multiply by 3 Multiply by 4 Multiply by 6 Multiply by 7 Multiply by 8 Multiply by 9 Square and Rectangles Unit squares and tiling - Area of Squares Area of rectangles click to return to Area Word Problems table of contents Slide 5 / 234 Slide 5 (Answer) / 234 Relate Multiplication to Addition Relate Multiplication to Addition There are 5 students. Each student is holding up both hands in the There are 5 students. Each student is holding up both hands in the air. How many hands are up in the air? air. How many hands are up in the air? Teacher Notes Teachers: choose 5 students to stand up. Have each student raise both hands. What are all of the ways you could figure out this answer? What are all of the ways you could figure out this answer? [This object is a pull tab]
Slide 6 / 234 Slide 7 / 234 Relate Multiplication to Addition Relate Multiplication to Addition Did you use addition? What would the number sentence look like? The Greene brothers went for a bike ride. If all four went riding, how many bicycle wheels would you see? 2 + 2 + 2 + 2 = 8 Click This is called repeated addition. Why do you think it is called this? What are all of the ways you could figure out this answer? Slide 8 / 234 Slide 9 / 234 Relate Multiplication to Addition Relate Multiplication to Addition Did you consider using multiplication? Which number sentences match the picture of three flowers with 7 How many bicycles were there? petals each? How many wheels did each bicycle have? What would the number sentence look like? 4 X 2 = 8 Click Repeated Addition Multiplication 7 + 7 + 7 + 7= 3 x 5= 6 + 6 + 6 = 3 + 3 + 3 = Once you are able to memorize your multiplication facts, you will realize that it is the quickest way to solve problems like the Greene brothers' 6 x 3= 3 x 7 = problem. 7 + 7 + 7= Slide 10 / 234 Slide 11 / 234 Relate Multiplication to Addition Relate Multiplication to Addition There are five jars. In each jar, there are 3 insects. Show all 5 jars with 3 insects in each jar in the space below. How would you write 4 x 6 = in a repeated addition problem? How many insects are there all together? What kind of picture could show these problems? What is the repeated addition sentence? What is the multiplication number sentence?
Slide 12 / 234 Slide 13 / 234 Relate Multiplication to Addition Multiplication Game Click to play Carl's Cookie Capers. How would you write 2 x 8 = in a repeated addition problem? What kind of picture could show these problems? Slide 14 / 234 Slide 14 (Answer) / 234 1 ) 2 x 5 = 5 + 5? 1 ) 2 x 5 = 5 + 5? True True False False Answer True [This object is a pull tab] Slide 15 / 234 Slide 15 (Answer) / 234 2 What would the repeated addition number sentence look 2 What would the repeated addition number sentence look like for the multiplication problem, 3 x 8 =? like for the multiplication problem, 3 x 8 =? A 8 + 8 = A 8 + 8 = B 3 + 3 + 3= B 3 + 3 + 3= C 8 x 3 = C 8 x 3 = Answer D 8 + 8 + 8 = D 8 + 8 + 8 = D [This object is a pull tab]
Slide 16 / 234 Slide 16 (Answer) / 234 3 What would the multiplication number sentence look like 3 What would the multiplication number sentence look like for the repeated addition problem, 5 + 5 + 5 =? for the repeated addition problem, 5 + 5 + 5 =? A 10 + 5 = A 10 + 5 = B 3 x 5= B 3 x 5= C 5 x 5 = C 5 x 5 = Answer D 3 x 3 = D 3 x 3 = B [This object is a pull tab] Slide 17 / 234 Slide 17 (Answer) / 234 4 What repeated addition number sentence would help you 4 What repeated addition number sentence would help you figure out the number of petals in the picture below? figure out the number of petals in the picture below? A 2 x 7 = A 2 x 7 = B 7 + 7 = B 7 + 7 = C 7 + 7 + 7 + 7 + 7 + 7 + 7 = C 7 + 7 + 7 + 7 + 7 + 7 + 7 = Answer D 10 + 4 = D 10 + 4 = B [This object is a pull tab] Slide 18 / 234 Slide 18 (Answer) / 234 5 What multiplication number sentence would help you figure 5 What multiplication number sentence would help you figure out the number of petals in the picture below? out the number of petals in the picture below? A 2 x 7 = A 2 x 7 = B 7 + 7 = B 7 + 7 = C 7 + 7 + 7 + 7 + 7 + 7 + 7 = C 7 + 7 + 7 + 7 + 7 + 7 + 7 = Answer D 10 + 4 = D 10 + 4 = A [This object is a pull tab]
Slide 19 / 234 Slide 20 / 234 What are Arrays? Arrays are rectangles made of organized rows and columns of objects to represent a certain number. An example, of the arrays for the number 6 are shown below. Arrays click to return to table of contents Slide 21 / 234 Slide 22 / 234 Using Arrays Using Arrays Now you try! Drag and place 8 soccer balls in an array on the field. When writing a multiplication number sentence for an array, write the How many different ways can you arrange the soccer balls so they are number of rows first. The second number should be the number in arranged into organized rows and columns? each row, or the number of columns. columns columns rows rows 2 x 4 4 x 2 Click to reveal the multiplication number sentence for each array. Slide 23 / 234 Slide 24 / 234 Using Arrays Using Arrays Drag the stars into the rectangle to make an array showing 2 x 5. How many stars will it take to complete the array? Each array below is an example of 6. What would the multiplication number sentence for each array be?
Slide 25 / 234 Slide 26 / 234 Using Arrays 6 Are the cats arranged in an array? Circle the peanuts to show other ways to make arrays showing 10. Yes No Slide 26 (Answer) / 234 Slide 27 / 234 6 Are the cats arranged in an array? 7 This is an array for what number? Yes No Answer No [This object is a pull tab] Slide 27 (Answer) / 234 Slide 28 / 234 7 This is an array for what number? 8 Which array is a model for 3 x 2? A the mice B the frogs C the flowers D none of the above Answer 12 [This object is a pull tab]
Slide 28 (Answer) / 234 Slide 29 / 234 8 Which array is a model for 3 x 2? 9 The multiplication number sentence for this array of shoes is 2 x 3. A the mice True B the frogs False C the flowers D none of the above Answer B [This object is a pull tab] Slide 29 (Answer) / 234 Slide 30 / 234 9 The multiplication number sentence for this array of shoes 10 What array is circled? is 2 x 3. A 2 x 6 True B 3 + 3 + 3 False C 12 x 1 D 3 x 4 Answer False [This object is a pull tab] Slide 30 (Answer) / 234 Slide 31 / 234 10 What array is circled? A 2 x 6 B 3 + 3 + 3 C 12 x 1 D 3 x 4 Multiplying by 1 and 0 Answer D [This object is a pull tab] click to return to table of contents
Slide 32 / 234 Slide 33 / 234 Multiplying by 0 Multiplying by 0 When multiplying a number by 0, try to remember relating it to addition. Can you explain what happens every time a number is multiplied by 0? For example, 8 x 0 can be thought of as 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0. What would that equal? Could you make an array using 8 x 0? This is called the Zero Property of Multiplication. Slide 34 / 234 Slide 35 / 234 Multiplying by 1 Multiplying by 0 When multiplying a number by 1, try to remember relating it to When multiplying a number by zero, we call it addition. For example, 8 x 1 can be thought of as 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1. Any number x 0 = 0 What would that equal? What would an array of 8 x 1 look like? Use the circles to show the array. Slide 36 / 234 Slide 37 / 234 Multiplying by 1 Multiplying by 1 When multiplying a number by one, we call it Can you explain what happens every time a number is multiplied by 1? Any number x 1 = itself This is called the Identity Property of Multiplication.
Slide 38 / 234 Slide 39 / 234 Multiplying by 1 and 0 Game Click the tire to play a game. Slide 40 / 234 Slide 40 (Answer) / 234 11 The answer to 10 x 0 is 10. 11 The answer to 10 x 0 is 10. True True False False Answer False [This object is a pull tab] Slide 41 / 234 Slide 41 (Answer) / 234 12 Sandra wants to buy prizes from the machines in front 12 Sandra wants to buy prizes from the machines in front of the store. She has to put in one coin in each of the store. She has to put in one coin in each machine. If there are 5 machines, how many coins machine. If there are 5 machines, how many coins will she need to buy a prize from each machine? will she need to buy a prize from each machine? A 1 A 1 B 5 B 5 Answer B C 0 C 0 D 4 D 4 [This object is a pull tab]
Slide 42 / 234 Slide 42 (Answer) / 234 13 What is the answer to any problem that involves 13 What is the answer to any problem that involves multiplying by 0? multiplying by 0? Answer 0 [This object is a pull tab] Slide 43 / 234 Slide 43 (Answer) / 234 14 ) 6 x 1 is an example of the Identity Property? 14 ) 6 x 1 is an example of the Identity Property? Yes Yes No No Answer Yes [This object is a pull tab] Slide 44 / 234 Slide 44 (Answer) / 234 15 15 Greg gives each of his customers 2 coupons when Greg gives each of his customers 2 coupons when they visit his store. If he hasn't had any customers they visit his store. If he hasn't had any customers today, how many coupons has he given out? today, how many coupons has he given out? A 2 A 2 B 1 B 1 C 0 C 0 Answer C [This object is a pull tab]
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