Algebra • Distributive Property
Total Page:16
File Type:pdf, Size:1020Kb
DO NOT EDIT--Changes must be made through “File info” CorrectionKey=B LESSON 4.4 Algebra • Distributive Property FOCUS COHERENCE RIGOR LESSON AT A GLANCE F C R Focus: Common Core State Standards Learning Objective 3.OA.B.5 Apply properties of operations as strategies to multiply Use the Distributive Property to find products by and divide. breaking apart arrays. Also 3.OA.A.1, 3.OA.A.3, 3.OA.A.4, 3.OA.C.7 MATHEMATICAL PRACTICES Language Objective MP4 Model with mathematics. MP7 Look for and make use of structure. Students give two ways you can use the MP8 Look for and express regularity in repeated reasoning. Distributive Property to find products. F C R Coherence: Materials Standards Across the Grades MathBoard, square tiles Before Grade 3 After 2.OA.A.1 3.OA.B.5 4.OA.A.2 F C R Rigor: Level 1: Understand Concepts....................Share and Show ( Checked Items) F C R For more about how GO Math! fosters Coherence Level 2: Procedural Skills and Fluency.......On Your Own within the Content Standards and Mathematical Progressions Level 3: Applications..................................Think Smarter and Go Deeper for this chapter, see page 189J. About the Math Professional Development Model the Distributive Property 8 3 7 Models help students develop a better understanding of concepts. StudentsAbout represent the the Math concepts first with concrete materialsProfessional or drawings, Development then with numbers and symbols. A model also helps students visualize the process and form a mental image. In this lesson, a factor is partitioned using an array to show why the Distributive Property works. The Distributive Property states that multiplying a sum by a number is the same as multiplying each addend by the number and then adding the products. 52 The goal of this lesson is to use the Distributive Property as a strategy to partition one of the factors. In this way, facts with greater products are shown as the sum of the products of two facts that students already know, making 8 × (5 + 2) multiplication faster and more flexible. (8 × 5) + (8 × 2) 40 + 16 = 56 Professional Development Videos 209A Chapter 4 1 ENGAGE Daily Routines with the Interactive Student Edition Common Core Essential Question Problem of the Day 4.4 How can you use the Distributive Property to find products? Ellis has 6 boxes. Each box holds 1 pencil. Write a number sentence to show how Making Connections many pencils Ellis has in all. Invite students to tell you what they know about multiplying by 1, 5, and 6. 6 × 1 = 6 What happens when you multiply any number by 1? The answer is the same number. Vocabulary Distributive Property What are different ways to multiply by 5? count by 5, add 5s What are different ways to multiply by 6? count by 6, add 6s Interactive Student Edition Multimedia eGlossary Learning Activity What is the problem the students are trying to solve? Connect the story to the problem. • How far does Lucia’s neighbor drive each day for work? 7 miles • How many days per week does Lucia’s neighbor drive to and from work? 5 days • What operation could you use to find the total number of miles Lucia’s neighbor drives for work per week? multiplication or addition • What multiplication expression could you use to find the total number of miles Lucia’s neighbors drives? 5 × 7 • What are different ways to solve 5 × 7? count by 7s, add 7 + 7 + 7 + 7 + 7, multiply 5 × 6 and add another 5 Literacy and Mathematics • Have students discuss the meaning of distribute in a larger context. Ask one student to distribute pieces of paper to each student to demonstrate the meaning of the word. • Have students write a short story about why Lucia wants to know how many miles his neighbor drives. How can you use the Distributive Property to find products? Lesson 4.4 209B LESSON 4.4 3.OA.B.5 Apply properties of operations as strategies to multiply and divide. 2 EXPLORE ALGEBRA Name Lesson 4.4 Unlock the Problem Distributive Property MATHEMATICAL PRACTICES Essential Question How can you use the Distributive Property to Operations and Algebraic find products? Thinking—3.OA.B.5 Also 3.OA.A.1, 3.OA.A.3, 3.OA.A.4, 3.OA.C.7 MATHEMATICAL PRACTICES Students should understand that they need MP1, MP7, MP8 to multiply the number of fish by the cost of UnlockUnlock the ProblemProblem each fish to find the total amount spent. Mark bought 6 new fish for his • Describe the groups in Have a volunteer read the definition of the aquarium. He paid $7 for each fish. this problem. How much money did he spend in all? Distributive Property. 6 groups of $7 Hands On Find 6 × $7. • Circle the numbers you will use to Activity solve the problem. You can use the Distributive Property MP4 Model with mathematics. Work with to solve the problem. students to make the array and break it apart. • How can you use the smaller arrays to find The Distributive Property states that multiplying a sum by a number is the sum—the answer to an addition problem the total? Find the total for each smaller array and same as multiplying each addend by the addends—the numbers being added add them together. number and then adding the products. Hands MP6 Attend to precision. On Materials ■ square tiles • Does breaking apart a larger array into Activity 2 smaller arrays make the problem easier Make an array with tiles to show Break apart the array to make two 6 rows of 7. smaller arrays for facts you know. to solve? Explain. Yes; Possible explanation: I can use basic facts I already know to find the total for each smaller array and then add the totals to find the answer. • Why do you think this is called the Distributive Property? Possible answer: because I am distributing 6 to both 2 and 5 to multiply. 6 × 7 = ■ 6 × 5 6 × 2 6 × 7 = ■ 6 × 7 = 6 × (5 + 2) Think: 7 = 5 + 2 Math 6 × 7 = (6 × 5) + (6 × 2) Multiply each addend by 6. Talk Use Math Talk to focus on 30 12 Math students’ understanding of using a 6 × 7 = _ + _ Add the products. Talk MATHEMATICAL PRACTICES 2 Reason Quantitatively model to draw conclusions and explain reasons 6 × 7 = _42 for their conclusions. Have several students What other ways could 42 you break apart the © Houghton Mifflin Harcourt Publishing Company So, Mark spent $_ for his new fish. draw their arrays on the board and write the 6 × 7 array? Possible answers: 6 × (6 + 1); 6 × (4 + 3) multiplication problems they used to find 6 × 7. Chapter 4 209 • Can you separate the array into 2 rows of 6 and 5 rows of 6 and get the same answer? Use the Distributive Property to see if you get the same answer. Possible 3 Differentiated answer: (2 × 6) + (5 × 6) = 12 + 30, or 42. Yes, it Reteach 4.4 2 Enrich 4.4 1 Instruction works; I get the same answer. Lesson 4.4 Lesson 4.4 Name Reteach Name Enrich ELL Strategy: Algebra • Distributive Property United Arrays A garden has 4 rows of 7 corn stalks. How many corn stalks Draw an array for each clue. Then use the arrays Check students’ Rephrase in all are in the garden? to solve each problem. arrays. You can use the Distributive Property to break an array 1. Craig spent $27 to buy 3 into smaller arrays to help you fnd the answer. calendars. The next day, he spent Explain the Distributive Property using an another $18 for more calendars. Find 4 3 7. Each calendar cost the same illustrated example from the lesson as support. amount. How many calendars did Step 1 Make an array to show 4 rows of 7. Craig buy? 5 calendars • In pairs, have students draw their own 4 rows of 7, or 4 3 7 Step 2 Break apart the array to make two 2. On Monday, Mrs. Jones spent array and break it apart, or distribute it, by smaller arrays for facts you know. $32 on 4 books. On Tuesday, she spent $16 on more books. Each book cost the same amount. How drawing the array and a dotted line where Step 3 Write the multiplication for the new many books did Mrs. Jones buy? arrays. Multiply and then add the products 4 3 4 1 4 3 3 they would break it apart. to fnd the answer. 16 1 12 5 28 6 books 4 3 7 5 (4 3 4) 1 (4 3 3) 4 3 7 5 16 1 12 4 3 7 5 28 3. Hailey spent $12 to buy 2 fish. Her cousin spent double the So, there are 28 corn stalks in all in the garden. • Have them write the multiplication amount on fish. Each fish cost the same amount. How many fish expression for the array and then for the Write one way to break apart the array. Possible answers are given. do Hailey and her cousin have Then fnd the product. altogether? broken apart, or distributed, array. 1. 2. 6 f sh 4. Explain how you used the arrays to solve each problem. • Have the pairs express the property or rule Possible answer: I drew two arrays for each problem then added the number of rows to in their own words in their Math Journal. (3 3 4) 1 (3 3 5); or (6 3 1) 1 (6 3 2); or f nd the number of items.