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 6 / 234 Relate Multiplication to Addition Relate Multiplication to Addition The Greene brothers went for a bike ride. There are 5 students. Each student is holding up both hands in the If all four went riding, how many bicycle wheels would you see? air. How many hands are up in the air? What are all of the ways you could figure out this answer? What are all of the ways you could figure out this answer?
Slide 7 / 234 Slide 8 / 234 Relate Multiplication to Addition Relate Multiplication to Addition Did you use addition? What would the number sentence look like? Did you consider using multiplication? 2 + 2 + 2 + 2 = 8 How many bicycles were there? Click How many wheels did each bicycle have? What would the number sentence look like? This is called repeated addition. Why do you think it is called this? 4 X 2 = 8 Click 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' problem. Slide 9 / 234 Slide 10 / 234 Relate Multiplication to Addition Relate Multiplication to Addition There are five jars. In each jar, there are 3 insects. Which number sentences match the picture of three flowers with 7 Show all 5 jars with 3 insects in each jar in the space below. How many insects are there all together? petals each? Repeated Addition Multiplication 7 + 7 + 7 + 7= What is the repeated addition sentence? 3 x 5= 6 + 6 + 6 = 3 + 3 + 3 = 6 x 3= 3 x 7 = What is the multiplication number sentence? 7 + 7 + 7= Slide 11 / 234 Slide 12 / 234 Relate Multiplication to Addition Relate Multiplication to Addition How would you write 4 x 6 = in a repeated addition problem? How would you write 2 x 8 = in a repeated addition problem? What kind of picture could show these problems? What kind of picture could show these problems?
Slide 13 / 234 Slide 14 / 234 Multiplication Game 1 ) 2 x 5 = 5 + 5? True Click to play Carl's Cookie Capers. False Slide 15 / 234 Slide 16 / 234 2 What would the repeated addition number sentence look 3 What would the multiplication number sentence look like like for the multiplication problem, 3 x 8 =? for the repeated addition problem, 5 + 5 + 5 =? A 8 + 8 = A 10 + 5 = B 3 x 5= B 3 + 3 + 3= C 5 x 5 = C 8 x 3 = D 3 x 3 = D 8 + 8 + 8 = Slide 17 / 234 Slide 18 / 234 5 What multiplication number sentence would help you figure 4 What repeated addition number sentence would help you 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 = D 10 + 4 = D 10 + 4 =
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 27 / 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 Slide 29 / 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
Slide 31 / 234 Slide 32 / 234 Multiplying by 0 When multiplying a number by 0, try to remember relating it to addition. For example, 8 x 0 can be thought of as 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0. Multiplying by 1 and 0 What would that equal? Could you make an array using 8 x 0? click to return to table of contents Slide 33 / 234 Slide 34 / 234 Multiplying by 0 Multiplying by 0 When multiplying a number by zero, we call it Can you explain what happens every time a number is multiplied by 0? Any number x 0 = 0 This is called the Zero Property of Multiplication. Slide 35 / 234 Slide 36 / 234 Multiplying by 1 Multiplying by 1 When multiplying a number by 1, try to remember relating it to addition. Can you explain what happens every time a number is multiplied by 1? For example, 8 x 1 can be thought of as 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1. What would that equal? What would an array of 8 x 1 look like? Use the This is called the Identity Property of Multiplication. circles to show the array.
Slide 37 / 234 Slide 38 / 234 Multiplying by 1 When multiplying a number by one, we call it Any number x 1 = itself Slide 39 / 234 Slide 40 / 234 Multiplying by 1 and 0 Game 11 The answer to 10 x 0 is 10. Click the tire to play a game. True False Slide 41 / 234 Slide 42 / 234 12 Sandra wants to buy prizes from the machines in front 13 What is the answer to any problem that involves of the store. She has to put in one coin in each multiplying by 0? machine. If there are 5 machines, how many coins will she need to buy a prize from each machine? A 1 B 5 C 0 D 4
Slide 43 / 234 Slide 44 / 234 15 Greg gives each of his customers 2 coupons when 14 ) 6 x 1 is an example of the Identity Property? they visit his store. If he hasn't had any customers Yes today, how many coupons has he given out? No A 2 B 1 C 0 Slide 45 / 234 Slide 46 / 234 Multiplying by 2 2 x 5 = 10 Factor Factor Product Multiply by 2 Factors are the numbers we multiply together to get to an answer which we call the product. When you are asked to multiply a number by the factor 2, what are some ways you could go about finding the answer? click to return to table of contents Slide 47 / 234 Slide 48 / 234 Multiplying by 2 Think of some words that mean 2. Click the numbers to reveal some.
Slide 49 / 234 Slide 50 / 234 Multiplying by 2 Multiplying by 2 can be thought of as doubling your factor. So, imagine that the problem 3 x 2 is 3 doubled, or 2 groups of 3. Double each set of animals below and write the multiplication number sentence to match. Slide 51 / 234 Slide 52 / 234 Multiplying by 2 Game 16 ) 2 x 0 = 2 Click the pencil to play a game. True False Slide 53 / 234 Slide 54 / 234 17 If you were to double 4, what would be your answer? 18 When you multiply a number by 2, the answer is always 2? A 2 Yes B 4 No C 6 D 8
Slide 55 / 234 Slide 56 / 234 19 Which number sentence matches the following word 20 Which picture below shows an array where 2 was a problem? factor? A peanuts Mr. Blake asked his students to take off their shoes for B flowers an activity and place them against the wall. If he has 9 students, how many shoes were along the wall? C pigs D none of the pictures A 9 + 1 = 10 B 9 x 2 = 9 C 9 x 9 = 81 D 9 x 2 = 18 Slide 57 / 234 Slide 58 / 234 Multiplying by 5 Fill in the chart below. Factor 1 2 3 4 5 6 7 x 5 Multiply by 5 What pattern do you see in the products of each factor? Could this be a rule? What do you notice about the digits in the ones place? click to return to table of contents Slide 59 / 234 Slide 60 / 234 Multiplying by 5 Let's Practice! Using what your remember from the table you created in the last slide, What items do you think of when 5 is mentioned? practice multiplying 5 and the number you roll on the 6-sided dice. Click each box for some ideas. Click the dice to roll again. 5 x = Can you use one of these items in a multiplication number story?
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