Develop Skills and Strategies Lesson 6 Part 1: Introduction CCSS Multiplication and Division in Word Problems 4.OA.A.2 In Lesson 5, you thought about equations that compare numbers using multiplication. In this lesson, you will solve those types of problems. Take a look at this problem. Hannah scored 3 goals last season. She scored 4 times as many goals this season. How many goals did Hannah score this season? Last season This season Explore It Use the math you already know to solve the problem. How many goals did Hannah score last season? Count to find the number of goals she scored this season. How can you use skip-counting to find the number of goals Hannah scored this season? Besides addition, what operation can you use to solve the problem? What is 4 times as many as 3? 44 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 1: Introduction Lesson 6 Find Out More You will often need to solve for some unknown amount, like when you found the number of goals Hannah scored. You used skip counting to find 4 times 3. You can also use a bar model. Last season 3 This season 3 3 3 3 ? The bar model can help you write an equation to solve the problem. 4 3 goals last season 5 goals this season Goals last season is known (3). Goals this season is unknown. You can use a symbol, such as an empty box or a question mark, to stand for the unknown number in the equation. 4 3 3 5 Reflect 1 What can you think of that has two times as many objects as something else? L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 45 Part 2: Modeled Instruction Lesson 6 Read the problem below. Then explore different ways to understand it. Janelle’s Market sells bags of 8 oranges. Simone needs 5 times that amount. Write and solve an equation to find the number of oranges Simone needs. Model It You can use models to help understand the problem. Number in one bag 8 Number Simone needs 8 8 8 8 8 ? Skip-count to find the total Simone needs: 8, 16, 24, 32, 40. Model It You can use the bar model to make an equation to help understand the problem. 5 3 oranges in one bag 5 total oranges needed The number of oranges in one bag is known (8). The total oranges needed is not known. 5 3 8 5 46 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 2: Guided Instruction Lesson 6 Connect It Now you will solve the problem from the previous page using an equation. 2 You don’t know how many oranges Simone needs. What part of the bar model shows how many she needs? 3 How does the bar model show how many oranges are in one bag? 4 How does the bar model show how many bags Simone needs? 5 How can you find “5 times as many” as 8? 6 Write an equation using numbers to show how many oranges Simone needs. Simone needs oranges. 7 Explain how you can write a multiplication equation from a bar model. Try It Use what you just learned to solve these problems. 8 Neil and Vincent are collecting cans. Neil has collected 10 cans and Vincent has collected 3 times as many cans as Neil. Write and solve an equation to find the number of cans Vincent has collected. 9 Mr. Cherry ate 6 times as many raisins as Mary. Mary ate 11 raisins. Write and solve an equation to find the number of raisins Mr. Cherry ate. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 47 Part 3: Modeled Instruction Lesson 6 Read the problem below. Then explore different ways to understand it. Juan found 3 times as many seashells at the beach as Jeremy found. Juan found 24 shells. Write and solve an equation to find the number of shells Jeremy found. Model It You can use a model to help understand the problem. Jeremy found one group of seashells. Juan found 3 times as many shells. Jeremy’s shells ? Juan’s shells ? ? ? 24 Divide 24 by 3 to find the number of seashells in each group: 8. Solve It You can use the model to make an equation to help understand the problem. 3 3 Jeremy’s shells 5 Juan’s shells The number of shells Juan found is known (24). The number Jeremy found is not known. 3 3 48 5 24 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 3: Guided Instruction Lesson 6 Connect It Now you will solve the problem from the previous page using an equation. 10 You don’t know the number of shells Jeremy found. In the bar model, what part shows the number of shells Jeremy found? 11 How does the bar model show how many shells Juan found? 12 How does the bar model show that 24 is 3 times another number? 13 How can you find what number times 3 is 24? 14 Write a division equation using numbers to show how many shells Jeremy found. Jeremy found shells. 15 Explain how you can write a division equation from a model. Try It Use what you just learned to solve these problems. 16 Monique and Wint are both reading the same book. Monique read 63 pages last weekend. She read 7 times as many pages as Wint. Write and solve an equation to find the number of pages Wint read. 17 The winning baseball team scored 4 times as many runs as their opponent. The winning team scored 8 runs. Write and solve an equation to find the number of runs their opponent scored. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 49 Part 4: Guided Practice Lesson 6 Study the model below. Then solve problems 18–20. Student Model There are twice as many boxes in Karina’s model as in her cousin’s model. Karina is 6 feet tall. Her cousin is 3 feet tall. How many times as tall as her cousin is Karina? Look at how you could show your work using a bar model. Cousin’s height 3 Karina’s height 3 3 6 Pair/Share How else could you solve this problem? What does it mean when the problem says 3 times as many? 33 5 6; 52 Solution: Karina is 2 times as tall as her cousin. 18 A small shrimp taco has 5 shrimp. There are 3 times as many shrimp in a large taco. How many shrimp are in a large taco? Write and solve an equation to find the answer. Show your work. Pair/Share Did you and your partner write the same, or different, equations? 50 Solution: L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 4: Guided Practice 19 Christina read 7 pages in a magazine. She read 5 times as many pages in a book. How many pages did Christina read altogether? Show your work. Lesson 6 I remember that multiplication and division are opposite operations! Pair/Share Solution: 20 Aida swam 7 laps in a pool. Kaya swam 28 laps. How many times the number of laps Aida swam did Kaya swim? Circle the letter of the correct answer. How can you check your answer? Does Jae Ho’s answer make sense? A4 B21 C35 D196 Jae Ho chose D as the correct answer. How did he get that answer? Solution: L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Pair/Share How did you and your partner know what operation to use? 51 Part 5: Common Core Practice Lesson 6 Solve the problems. 1 Kyle sold 28 boxes of fruit for a fundraiser. Omar sold 2 times as many boxes of fruit as Kyle sold. What is the total number of boxes that Kyle and Omar sold? A84 B56 C42 D14 2 Raoul biked 11 miles last week. Jackson biked 22 miles last week. Jackson biked how many times as many miles as Raoul? Which equation can help you answer the question? A22 2 11 5 h B22 4 11 5 h C11 3 22 5 h D11 1 22 5 h 3 Which problems can be solved using the equation 3 3 9 5 A? Circle the letter of all that apply. 52 A Pam is 9 years old. She is 3 times as old as Kate. How old is Kate? B Marco is making 9 apple tortes. He needs 3 apples for each torte. How many apples does he need? C Three groups of actors are performing plays at a festival. There are 9 actors in each group. How many actors are performing? D An art class meets 3 times a week for 9 weeks. How many times does the class meet? E Judy found 3 acorns. Aaron found 3 times as many acorns as Judy. How many acorns did Aaron find? L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 5: Common Core Practice Lesson 6 4 Maria has 32 postcards. Henry has h postcards. Maria has 4 times as many postcards as Henry. Choose Yes or No to indicate whether each statement is true. a. The number of Henry’s postcards can be represented by the expression 32 4 4. Yes No b. Henry has 6 postcards. Yes No Yes No c. The number of Henry’s postcards can be found by solving the equation 32 5 4 3 h. 5 Viet learned 25 new spelling words last week. He learned 5 times as many words as Max. How many words did Max learn? Draw a bar model to find the number of words Max learned. Show your work. Answer Max learned new spelling words last week. 6 Mr. Naik traveled 18 hours on vacation last summer. Miss Cooper traveled 3 hours on vacation last summer. How many times as many hours did Mr. Naik travel as Miss Cooper? Write an equation to find the answer. Show your work. Answer Mr. Naik traveled times as many hours on vacation as Miss Cooper. Self Check Go back and see what you can check off on the Self Check on page 37. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 53 Develop Skills and Strategies Lesson 6 (Student Book pages 44–53) Multiplication and Division in Word Problems Lesson Objectives The Learning Progression •Use drawings and symbols to represent a multiplicative comparison problem. In this lesson, students will apply what they know about multiplicative comparisons to solve multiplication and division problems. Students will model problems involving “times as many,” write a number sentence using symbols, and solve for the unknown. •Use an equation to solve for the unknown in a multiplicative comparison problem. PrerequisiTe Skills •Recall basic multiplication and division facts. •Interpret products of whole numbers, including multiplicative comparisons. •Use arrays, drawings, number lines, and equations to solve multiplication and division problems. •Determine the unknown whole number in a multiplication or division equation. •Understand the relationship between multiplication and division. Vocabulary unknown: a missing number in an equation symbol: an object used to stand for an unknown number in an equation For example, students may solve a multiplication problem in which they know the number of rings that Sonja has (4) and are told that Mia has 3 times as many. Or, students may solve a division problem to find the number of rings that Sonja has. They create models and write number sentences using symbols to solve for the unknown. Developing student understanding and application of multiplicative comparisons in Grade 4 develops a foundation for understanding multiplication as scaling when multiplying by a fraction; for example, students will later understand one fourth times a number as one fourth as many. Teacher Toolbox Review the following key terms. multiplication: an operation used to find the total number of items in equal-sized groups Ready Lessons product: the result of multiplying numbers together Tools for Instruction factors: the numbers you multiply Interactive Tutorials Teacher-Toolbox.com Prerequisite Skills 4.OA.A.2 4.OA.2 ✓✓ ✓ ✓ ✓ ✓✓ ✓ division: an operation used to separate a number of items into equal-sized groups equation: a mathematical sentence that uses an equal sign (5) to show that two expressions have the same value CCSS Focus 4.OA.A.2 Multiply or divide to solve word problems involving multiplicative comparison, e.g. by using drawings and equations with a symbol for the unknown number to represent the problem, distinguishing multiplicative comparison from additive comparison. STANDARDS FOR MATHEMATICAL PRACTICE: SMP 2, 3, 4, 5, 7 (See page A9 for full text.) 50 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 1: Introduction Lesson 6 At a Glance Students review thinking about multiplication as a comparison (times as many). They use models and skip counting to solve a multiplication problem. Develop skills and strategies Lesson 6 Part 1: introduction ccss 4.oa.a.2 Multiplication and Division in Word Problems in Lesson 5, you thought about equations that compare numbers using multiplication. in this lesson, you will solve those types of problems. take a look at this problem. Step By Step •Tell students that this page models how to find the product for a problem that compares two numbers using the words “times as many.” Hannah scored 3 goals last season. She scored 4 times as many goals this season. How many goals did Hannah score this season? Last season This season •Have students read the problem at the top of the page. •Work through Explore It as a class. Ask students to work with a partner to answer the first two questions and have them share their responses. explore it •Draw 3 soccer balls on the board. Use the drawing to model 3 goals last season by circling the group of 3 soccer balls. Add 3 more balls, circle them, and say, “2 times as many.” Continue until students see that 4 3 3 is this season’s score (12) and that it is 4 times as large as last season’s score. •Ask student pairs to explain their answers for the last three questions on the page. Use the Mathematical Discourse questions to help clarify and extend students’ thinking about the problem. use the math you already know to solve the problem. How many goals did Hannah score last season? 3 Count to find the number of goals she scored this season. 12 How can you use skip-counting to find the number of goals Hannah scored this season? 3, 6, 9, 12 Besides addition, what operation can you use to solve the problem? multiplication What is 4 times as many as 3? 44 12 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. •You may wish to assess students, understanding by asking, What does the product tell you in this problem? Concept Extension Compare different meanings of a product in a multiplication problem. •Point out to students that when they find 4 times 3, they are finding the product of 4 and 3. Review what the product 12 tells us in the soccer ball problem. [It tells us what number is 4 times as many as 3. 12 is the number of goals Hannah scored this year, compared to last year (3).] •Give students this problem and ask what the product tells you: Chloe scored 3 goals in each game. She played 4 games. How many points did she score in all? The product tells the total number of goals for all 4 games. Mathematical Discourse •What are you comparing in this problem? You are comparing last year’s goals (3) to this year’s goals. •Which would be more: 4 times as many or 8 times as many? How do you know? Look for answers that show students understand that 8 times as many is more because it means 8 copies of some amount instead of only 4 copies. 8 copies is more than 4 copies because 8 is more than 4. •Ask: How is the meaning of the products in the Hannah and Chloe problems different? [In the Hannah problem, the product tells what is 4 times as many as 3. In the Chloe problem, the product tells the total number of goals.] L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 51 Part 1: Introduction Lesson 6 At a Glance Students see a bar model that represents the multiplication comparison and then see how to write an equation from that model. Step By Step •Read Find Out More as a class. •Help students connect the 4 bars of length 3 to the 4 sets of 3 soccer balls. •Point out that a number sentence uses numbers and symbols to describe a problem and helps make it clear what you know and what you need to find. •Use the problems on the page to point out what is “known,” what the “unknown” is, and how “boxes” or a question mark can stand for the unknown. Part 1: introduction Lesson 6 Find out More You will often need to solve for some unknown amount, like when you found the number of goals Hannah scored. You used skip counting to find 4 times 3. You can also use a bar model. Last season 3 This season 3 3 3 3 ? The bar model can help you write an equation to solve the problem. 4 3 goals last season 5 goals this season Goals last season is known (3). Goals this season is unknown. You can use a symbol, such as an empty box or a question mark, to stand for the unknown number in the equation. 4335 reflect 1 What can you think of that has two times as many objects as something else? Possible answer: a car has 2 times as many wheels as a bicycle. •Have students read and reply to the Reflect directive. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Visual Model From Models to Symbols to Products Materials: White boards or paper and markers •Draw 2 small circles on the board. Underneath, write “4 times as many.” •Ask students to work in pairs to make a drawing of 4 times as many circles as you drew. Have them write a number sentence underneath using a “box” to show the unknown (product). Ask pairs to hold up their white board or paper and say the number sentence aloud. [4 3 2 5 8 or 2 3 4 5 8] Copying is not permitted. 45 Real-World Connection Encourage students to think of times when they could have a certain number of “times as many” more of something than someone else. Ask a few students to share situations. Students may describe situations comparing with friends or siblings amounts of money, treats, time, distance, and so forth. If students need help getting started, remind them that “twice as many” is a multiplication comparison. •Draw 3 circles with the label “two times as many” and have pairs create drawings and write number sentences. [2 3 3 5 6 or 3 3 2 5 6] •Draw 2 circles with the label “6 times as many” and have students do the same. [6 3 2 5 12 or 2 3 6 5 12] 52 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 2: Modeled Instruction Lesson 6 At a Glance Part 2: Modeled instruction Students use models and an equation to help them understand a problem. read the problem below. then explore different ways to understand it. Janelle’s Market sells bags of 8 oranges. Simone needs 5 times that amount. Step By Step Write and solve an equation to find the number of oranges Simone needs. •Read the problem at the top of the page as a class. Model it you can use models to help understand the problem. •Read the first Model It. Make a simple drawing to show one bag of 8 oranges on the board and point out that Simone needs “5 times as many.” •Read the second Model It together. Underneath the drawing on the board, write the equation 8 3 5 5 . Explain that both the picture and the number sentence describe the problem. There are 8 oranges and Simone wants “5 times as many.” •Note: Students may find it easier to write the equation starting with the number “8” because that is the quantity in one bag, and then write “3 5.” Point out another way to say the same thing: “5 times as many as 8.” Write the sentence as 5 3 8. Remind students that, either way, the product is 40. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Number in one bag 8 Number Simone needs 8 8 8 8 8 ? •Quickly draw 4 more bags labeled “8” and ask a volunteer to count to find the total number of oranges Simone needs. Help students make the connection to using skip counting (counting by 8s) as a way to find the product. Ask students, When you are skip counting to find a product, how do you know when to stop counting? [When I’ve skipped a certain number of times. The problem tells me how many times.] •Ask students to compare the pictorial representation on the board to the bar model in their books. Be sure they see that each segment of the bar model represents one bag of oranges. Bar models are sometimes easier to draw than pictures, but they serve the same purpose. Lesson 6 Skip-count to find the total Simone needs: 8, 16, 24, 32, 40. Model it you can use the bar model to make an equation to help understand the problem. 5 3 oranges in one bag 5 total oranges needed The number of oranges in one bag is known (8). The total oranges needed is not known. 5385 46 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Concept Extension Multiplying Strategies: Dots and Circles Materials: paper or white board and markers •Explain to students that there are other quick strategies they can use to find multiplication products if they don’t remember a multiplication fact or if skip counting becomes difficult (like counting by 7s or 8s). •Write the problem 5 3 8 on the board. Draw 5 circles and quickly draw 8 dots in each. Explain that if you don’t know a product, you can make a quick “circle and dots” drawing to model the problem and then quickly count to find the product. Show them that they could also draw 5 dots and circle it, then add another 5 dots and circle it, until they have 8 groups of 5 dots. 53 Part 2: Guided Instruction Lesson 6 At a Glance Students revisit the problem on page 46 to solve the problem using an equation. Step By Step •Read the Connect It questions. Ask students to answer the questions on their own or with a partner. Ask students to share their answers for problems 3 and 4 with the class. •For problem 6, ask a volunteer to model what they thought or said to themselves to create an equation from the bar model. Emphasize that whatever the drawing shows, they can show the same thing using numbers and symbols in a number sentence. Part 2: guided instruction Lesson 6 connect it now you will solve the problem from the previous page using an equation. 2 You don’t know how many oranges Simone needs. What part of the bar model shows how many she needs? the question mark. 3 How does the bar model show how many oranges are in one bag? each little box has an 8 in it. 4 How does the bar model show how many bags Simone needs? there are 5 little boxes. 5 How can you find “5 times as many” as 8? Multiply 5 3 8. 6 Write an equation using numbers to show how many oranges Simone needs. 5 3 8 5 40 Simone needs 40 oranges. 7 Explain how you can write a multiplication equation from a bar model. Possible explanation: Look at how many little boxes there are and how many are in each box. Multiply how many boxes by how many are in each box to get the total. SMP Tip: Asking students to think carefully and explain how they created a number sentence from a drawing and problem helps students think deeply about the meaning of the quantities and their relationships. (SMP 2) try it use what you just learned to solve these problems. 8 Neil and Vincent are collecting cans. Neil has collected 10 cans and Vincent has collected 3 times as many cans as Neil. Write and solve an equation to find the number of cans Vincent has collected. 10 3 3 5 v; v 5 30; vincent has collected 30 cans 9 Mr. Cherry ate 6 times as many raisins as Mary. Mary ate 11 raisins. Write and solve an equation to find the number of raisins Mr. Cherry ate. 11 3 6 5 c; c 5 66; Mr. cherry ate 66 raisins L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 47 TRY IT solutions 8Solution: 30 cans; Students may see the problem as 3 “times as many” cans as 10 and write 3 3 10 5 30, or they may write 10 3 3 5 30 (that’s 10 three times), knowing they can change the order of factors. Concept Extension Promote metacognition. When students explain how they wrote an equation from a model, use it as an opportunity to list some questions students can ask themselves when they are trying to make sense out of a problem, such as What does each number in the problem tell me? Do I know the total amount? Am I trying to find the total amount? Do I see groups in the drawing? Do I see how many are in each group? List the questions in the room and encourage students to ask them as they make sense of problems. 54 9Solution: 66 raisins; Students may see the problem as 6 “times as many” as 11 raisins and write 6 3 11 5 66, or they may write 11 3 6 5 66 (that’s 11 six times), knowing they can change the order of factors. ERROR ALERT: Students who wrote an incorrect product may not be using a workable strategy, such as using a quick drawing to find the large product or using repeated addition when they do not know the multiplication fact 6 3 11 5 66. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 3: Modeled Instruction Lesson 6 At a Glance Part 3: Modeled instruction Students explore “times as many” situations in which they find a missing factor or use division to solve the problem. Lesson 6 read the problem below. then explore different ways to understand it. Juan found 3 times as many seashells at the beach as Jeremy found. Juan found 24 shells. Write and solve an equation to find the number of shells Jeremy found. Step By Step Model it •In this lesson, this is the first time that students encounter a “times as many” problem in which they must find a missing factor or use division to solve the problem. you can use a model to help understand the problem. Jeremy found one group of seashells. Juan found 3 times as many shells. Jeremy’s shells ? Juan’s shells ? ? ? 24 •Read the problem. Explain to students that they need to think about what they know and don’t know in the problem. Guide their thinking by asking questions such as, Do we know how many shells Juan found? [24 shells. That’s 3 times as many as Jeremy.] Do we know how many Jeremy found? [no] Do either of the boys have more than 24 shells? [no] How do you know? Divide 24 by 3 to find the number of seashells in each group: 8. solve it you can use the model to make an equation to help understand the problem. 3 3 Jeremy’s shells 5 Juan’s shells The number of shells Juan found is known (24). The number Jeremy found is not known. 33 5 24 •Draw the model in Model It on the board. Help students understand why you know that there are 3 equal groups. Ask students how to figure how many should be in each group. •Underneath the picture, write the equation from Solve It and make a clear connection that each number and symbol describes what the picture and problem describes. 48 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. SMP Tip: Use the following Concept Extension activity to give students an opportunity to practice constructing arguments and reasoning quantitatively to show their understanding. (SMP 3) Concept Extension Do You Agree? Have students work in pairs to discuss whether or not they agree with the following statement, and why. If possible, ask them to give an example to prove their point. Statement: When you see the words “times as many” in a problem, you always must find the product. Students should be able to explain that in a “times as many” problem they could be finding the product (like the “bags of oranges” problem) or dividing to find a missing factor (like the seashell problem). L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Mathematical Discourse •How could the number 24 in this problem be both a product and a dividend? If you think of the problem as having a missing factor, then 24 is the product. If you think of it as dividing, then 24 is the dividend. In both cases, you want to know the number of shells Jeremy found. •How is this problem different from the “times as many” problems you solved earlier in this lesson? In this problem, division is used to find the answer. The answer wasn’t the product but was a missing factor. 55 Part 3: Guided Instruction Lesson 6 At a Glance Students solve a division and multiplication problem involving “times as many” using an equation. Step By Step •Read the Connect It questions. Ask students to answer the questions on their own or with a partner. Have students to share their answers for problems 10 through 12 with the class. •Be sure students see that each section of the bar model represents the same amount: the number of shells Jeremy found. •Point students’ attention to problem 13. After inviting volunteers to share their thinking, explain that you can think about the problem in two different ways: one is to find the missing factor (What number times 3 is equal to 24?) or to find the size of a group (What is 24 shared equally in 3 groups?) and get 8. •Invite students to share and discuss their answers for problem 15. Help students acknowledge the different ways to think about a problem and still arrive at the same answer mathematically. Part 3: guided instruction connect it now you will solve the problem from the previous page using an equation. 10 You don’t know the number of shells Jeremy found. In the bar model, what part shows the number of shells Jeremy found? the little box with the question mark. 11 How does the bar model show how many shells Juan found? the bar with his name on it is labeled 24. 12 How does the bar model show that 24 is 3 times another number? the 3 little boxes altogether are the same length as the 24 bar. 13 How can you find what number times 3 is 24? Find 3 3 To help students make connections between what to think, say, and write for an equation that has a missing factor, write the following sentence frame on the board or wall: “What number times 5 ?” Visual Model Represent the problem with a picture. To help students visualize the problem in another way, draw 24 shells or dots on the board to stand for 24 shells. Tell students that “3 times as many” means that there must be 3 times 1 group. Draw 3 empty (large) circles. Explain that they know Juan found 24 shells. They are comparing what Jeremy found (in one circle) to what Juan found (24). Write the equation 3 3 5 24. Help them to think of a multiplication fact to find the missing factor. Relate the missing factor to the number in one group and to the number of shells Jeremy collected. 56 5 24 or find 24 4 3 = . 14 Write a division equation using numbers to show how many shells Jeremy found. 24 4 3 5 8 Jeremy found 8 shells. 15 Explain how you can write a division equation from a model. Possible explanation: i look at how many little boxes there are and how much they equal altogether. i can divide the total by the number of little boxes to see how much each box is. try it use what you just learned to solve these problems. 16 Monique and Wint are both reading the same book. Monique read 63 pages last weekend. She read 7 times as many pages as Wint. Write and solve an equation to find the number of pages Wint read. 63 5 7 3 w or 63 4 7 5 w; w 5 9; 9 pages 17 The winning baseball team scored 4 times as many runs as their opponent. The winning team scored 8 runs. Write and solve an equation to find the number of runs their opponent scored. 4 3 r 5 8 or 8 4 2 5 r; r 5 2; 2 runs L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC ELL Support Lesson 6 Copying is not permitted. 49 TRY IT solutions 16 Solution: 9 pages; Students may write a multiplication equation to find the missing factor, 7 3 w 5 63, or a division equation, 63 4 7 5 w, to show how many pages times 7 is 63 pages. 17 Solution: 2 runs; Students may use a model to show 8 runs as 4 times the opponent’s score and write an equation 8 4 4 5 r or 4 3 r 5 8. ERROR ALERT: Students may see “times as many” and multiply 4 3 8. Help students see that the score of 8 is the winning team’s score, which is 4 times their opponent’s score. The unknown is the opponent’s score. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Part 4: Guided Practice Lesson 6 Part 4: guided Practice Lesson 6 study the model below. then solve problems 18–20. Student Model There are twice as many boxes in Karina’s model as in her cousin’s model. Karina is 6 feet tall. Her cousin is 3 feet tall. How many times Part 4: guided Practice Lesson 6 19 Christina read 7 pages in a magazine. She read 5 times as many pages in a book. How many pages did Christina read altogether? Show your work. as tall as her cousin is Karina? Magazine pages 7 Book pages 7 I remember that multiplication and division are opposite operations! Look at how you could show your work using a bar model. Cousin’s height 3 Karina’s height 3 7 7 7 7 35 3 7 1 35 5 42 Pair/share 6 Pair/share How else could you solve this problem? What does it mean when the problem says 3 times as many? 33 5 6; Solution: 42 pages 52 Solution: karina is 2 times as tall as her cousin. 20 Aida swam 7 laps in a pool. Kaya swam 28 laps. How many times 18 A small shrimp taco has 5 shrimp. There are 3 times as many shrimp in a large taco. How many shrimp are in a large taco? Write and solve an equation to find the answer. Show your work. 50 a 4 b 21 c 35 Jae Ho chose D as the correct answer. How did he get that answer? Solution: jae ho multiplied the number of laps each girl swam instead of dividing them. Solution: 15 shrimp L6: Multiplication and Division in Word Problems L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Does Jae Ho’s answer make sense? D 196 5 shrimp in a small taco 33 15 in a large taco Pair/share Did you and your partner write the same, or different, equations? the number of laps Aida swam did Kaya swim? Circle the letter of the correct answer. How can you check your answer? Copying is not permitted. ©Curriculum Associates, LLC Copying is not permitted. Pair/share How did you and your partner know what operation to use? 51 At a Glance solutions Students use equations to solve multiplication and division problems involving “times as many.” They show understanding of multiplication and division as opposite operations to check their answers. Ex Solution: Karina is 2 times as tall as her cousin; the student model shows using a bar model to find how many 3s make 6. Students may also see 6 4 3 5 2 from the model. Step By Step 18 Solution: 5 3 3 5 15 shrimp; Students may also write 3 3 5 5 15 for “3 times as many of the 5 shrimp.” (DOK 1) •Ask students to solve the problems individually. •When students have completed each problem, have them Pair/Share to discuss their solutions with a partner and be ready to share with the class. •Be sure students know what is meant by “operation” and “opposite operations” and how they can use the opposite operation to check their answers. For example, students find the quotient for 15 4 3 (5). They can multiply 3 3 5 and should get the product 15. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 19 Solution: 42 pages; See sample student work above. (DOK 1) 20 Solution: A; Students may have divided 28 by 7 or thought, “how many times as many as 7 is 28?” Explain to students why the other two answer choices are not correct: B is not correct because it is the difference between 7 and 28. C is not correct because it is 7 greater than 28. (DOK 3) 57 Part 5: Common Core Practice Part 5: common core Practice Lesson 6 Solve the problems. 1 Lesson 6 Part 5: common core Practice 4 84 B 56 C 42 D 14 5 2 3 Raoul biked 11 miles last week. Jackson biked 22 miles last week. Jackson biked how many times as many miles as Raoul? Which equation can help you answer the question? A 22 2 11 5 h B 22 4 11 5 h C 11 3 22 5 h D 11 1 22 5 h Maria has 32 postcards. Henry has h postcards. Maria has 4 times as many postcards as Henry. Choose Yes or No to indicate whether each statement is true. Kyle sold 28 boxes of fruit for a fundraiser. Omar sold 2 times as many boxes of fruit as Kyle sold. What is the total number of boxes that Kyle and Omar sold? A Lesson 6 a. The number of Henry’s postcards can be represented by the expression 32 4 4. b. Henry has 6 postcards. c. The number of Henry’s postcards can be found by solving the equation 32 5 4 3 h. 3 Yes No Yes 3 No 3 Yes No Viet learned 25 new spelling words last week. He learned 5 times as many words as Max. How many words did Max learn? Draw a bar model to find the number of words Max learned. Show your work. Max 5 Viet 5 5 5 5 5 25 Which problems can be solved using the equation 3 3 9 5 A? Circle the letter of all that apply. A Pam is 9 years old. She is 3 times as old as Kate. How old is Kate? B Marco is making 9 apple tortes. He needs 3 apples for each torte. How many apples does he need? C Three groups of actors are performing plays at a festival. There are 9 actors in each group. How many actors are performing? D An art class meets 3 times a week for 9 weeks. How many times does the class meet? E Judy found 3 acorns. Aaron found 3 times as many acorns as Judy. How many acorns did Aaron find? Answer Max learned 6 5 new spelling words last week. Mr. Naik traveled 18 hours on vacation last summer. Miss Cooper traveled 3 hours on vacation last summer. How many times as many hours did Mr. Naik travel as Miss Cooper? Write an equation to find the answer. Show your work. Possible equation: 18 4 3 5 Answer Mr. Naik traveled 6 or 3 3 5 18 times as many hours on vacation as Miss Cooper. self check Go back and see what you can check off on the Self Check on page 37. 52 L6: Multiplication and Division in Word Problems L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. ©Curriculum Associates, LLC Copying is not permitted. 53 At a Glance 4Solution: a. Yes; b. No; c. Yes (DOK 2) Students multiply and divide to solve word problems involving multiplicative comparison that might appear on a mathematics test. 5Solution: 5; See sample student work above. 25 is 5 times the number of words Max learned, so Max learned 5 words. (DOK 1) solutions 6Solution: 6; 18 4 3 5 6 or 3 3 6 5 18 or 6 3 3 5 18 (DOK 1) 1Solution: A; Students may see the problem as 28 3 2 5 56 and 56 1 28 5 84. (DOK 2) 2Solution: B; Students may think 22 divided by a number equals 11. (DOK 1) 3Solution: B; If there are 3 apples for each of 9 tortes, then 3 3 9 is equal to the total apples, A. C; If there are 9 actors in each of 3 groups, then 3 3 9 is equal to the total actors, A. D; If there are 3 art classes each week for 9 weeks, then 3 3 9 is equal to the total art classes, A. (DOK 2) 58 L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. Differentiated Instruction Lesson 6 Assessment and Remediation •Ask students to write an equation to solve this problem: Jake has 12 bean plants in his garden. He has 3 times as many as Simone has in her garden. How many plants does Simone have? [4] •For students who are struggling, use the chart below to guide remediation. •After providing remediation, check students’ understanding. Ask students to solve this problem: Sophia counted 10 cars going by. That is 5 times as many cars as Carla counted. How many cars did Carla count? [2] •If a student is still having difficulty, use Ready Instruction, Level 4, Lesson 5. If the error is . . . Students may . . . To remediate . . . 12 3 3 5 36 think that “times as many” only indicates multiplication. Have students underline each number in the problem. Ask what each number tells them. Help students verbalize what is not known in the problem. Ask what it means when the problem says “Jake has 3 times as many as Simone.” [12 is 3 times as many.] Then use drawings and an equation to find the quotient. 12 2 3 5 9 think a comparison requires subtraction. Remind students that some comparisons involve multiplication, like when one number is a certain “times as many” as another number. Use number lines and drawings to show what “times as many” means. 4 “times as many” as 3 means that they will see “3” objects and then multiply that quantity by 4 because another number is “4 times as many.” 12 1 3 5 15 Add to find a larger number. Instead, they should multiply to compare and understand that one number is a certain “times as many” as another number. Use number lines and drawings to show what “times as many” means. 4 “times as many” as 3 means that they will see “3” objects and then multiply that quantity by 4 because another number is “4 times as many.” Hands-On Activity Challenge Activity Use counters to solve “times as many” problems. Write a problem for a given product or dividend. Materials: Counters Write these products on the board: 36, 24, and 45. Challenge students to choose one of these numbers to be a product or dividend in a “times as many” problem. Direct them to write the problem for a partner to solve. The partner will write an equation and solve the problem. The problem author should ask the partner, “How do you know that the equation describes the problem? How do you know the solution is correct?” Distribute counters to each student. Write the following sentence frame on the board: What if you have counters and I have times as many counters as you have? Then I have counters. Direct each student to think of numbers to correctly complete the sentence. Have them use counters to model the problem and say the sentence aloud to a partner. Ask a few students to share and have a volunteer write the number sentence on the board that matches the student’s sentence frame. L6: Multiplication and Division in Word Problems ©Curriculum Associates, LLC Copying is not permitted. 59
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