Multiplication and Division Fact Families Objectives To review fact families and the Multiplication/Division Facts Table; and to guide children as they practice multiplication and division facts. www.everydaymathonline.com ePresentations eToolkit Algorithms Practice EM Facts Workshop Game™ Teaching the Lesson Key Concepts and Skills • Use Fact Triangles and the Facts Table to generate multiplication and division fact families. [Operations and Computation Goal 3] • Look for patterns on the Facts Table. [Patterns, Functions, and Algebra Goal 1] • Explore the inverse relationship between multiplication and division fact families. [Patterns, Functions, and Algebra Goal 2] Family Letters Assessment Management Common Core State Standards Ongoing Learning & Practice Practicing with ×, ÷ Fact Triangles ×, ÷ Fact Triangles Children practice multiplication and division with Fact Triangles. Math Boxes 4 6 Math Journal 1, p. 90 Children practice and maintain skills through Math Box problems. Home Link 4 6 • Apply the turn-around rule (Commutative Property of Multiplication). [Patterns, Functions, and Algebra Goal 4] Math Masters, pp. 99–102 Children practice and maintain skills through Home Link activities. Key Activities Curriculum Focal Points Interactive Teacher’s Lesson Guide Differentiation Options READINESS Practicing Multiplication Facts with a Calculator Math Masters, p. 103 calculator Children skip count with calculators. ENRICHMENT Examining a Pattern Math Masters, p. 98 or Math Journal 1, inside front cover per partnership: half-sheet of paper, highlighters (optional) Children examine a pattern in the Multiplication/Division Facts Table. Children use the Multiplication/Division Facts Table and Fact Triangles to find fact families and to practice multiplication and division facts. Ongoing Assessment: Recognizing Student Achievement Use the Math Message. [Patterns, Functions, and Algebra Goal 2] Key Vocabulary Multiplication/Division Facts Table Materials Math Journal 1, inside front cover Math Journal 1, Activity Sheets 1 and 2; Activity Sheets 3 and 4 (optional) Student Reference Book, pp. 52 and 53 Home Link 45 Math Masters, p. 98 (optional); p. 421 transparencies of Math Masters, pp. 98 and 421 (optional) scissors slate paper envelope half-sheet of paper Advance Preparation When you send Home Link 46 home, copy and attach Math Masters, pages 101 and 102. Teacher’s Reference Manual, Grades 1–3 pp. 16, 17 272 Unit 4 Multiplication and Division 272_EMCS_T_TLG1_G3_U04_L06_576809.indd 272 2/11/11 1:59 PM Getting Started Mental Math and Reflexes Math Message Have children count chorally. They may use number grids, number lines, or calculators as needed. Write the +,- fact family for the numbers 2, 2, and 4 on a half-sheet of paper. Skip count forward and backward by 2s, 5s, and 10s. Skip count forward and backward by 3s and 6s. Skip count forward and backward by 4s and 8s. Home Link 4 5 Follow-Up Have partners discuss the multiplication-fact shortcuts they like the best. 1 Teaching the Lesson Math Message • 12 WHOLE-CLASS ACTIVITY ×, ÷ Follow-Up 4 Ask a volunteer to share the fact family for 2, 2, and 4. 2 + 2 = 4, and 4 - 2 = 2. The fact family 2, 2, and 4 is a doubles fact family. Mention that just like addition and subtraction fact families, there are also multiplication and division fact families. Ongoing Assessment: Recognizing Student Achievement Math Message 3 3 × 4 = 12 12 ÷ 4 = 3 4 × 3 = 12 12 ÷ 3 = 4 Fact family for the numbers 4, 3, and 12 Use the Math Message to assess children’s progress toward using the +, -, and = symbols. Children are making adequate progress if they are able to write the fact family. Some children may notice that the same numbers (2, 2, and 4) can be used to write a multiplication fact and a division fact using the ×, ÷, and = symbols. [Patterns, Functions, and Algebra Goal 2] Teaching Aid Master Name Date Time Multiplication/Division Fact Triangle Introducing Multiplication/ WHOLE-CLASS ACTIVITY Division Fact Families (Math Masters, p. 421) Use a transparency of a blank Fact Triangle (Math Masters, page 421) or draw one on the board. Write the three numbers from a multiplication fact—for example, 3, 4, and 12—in the corners of the triangle. Be sure the product is at the top under the large dot. ⫻,⫼ Ask volunteers to name the fact family (the two multiplication facts and two division facts) for those numbers. 3 × 4 = 12, 4 × 3 = 12, 12 ÷ 3 = 4, and 12 ÷ 4 = 3 Math Masters, p. 421 Lesson 4 6 EM3cuG3TLG1_273-277_U04L06.indd 273 273 12/22/10 1:48 PM Write a few more triplets of numbers in the triangle. Children write the fact families on their slates. A volunteer reads the results as the others check their slates. In the previous lesson, children used arrays to demonstrate a turn-around rule for multiplication. Ask: Is there a turn-around rule for the division facts in each fact family? No Have children give examples to show that there is no turn-around rule for division; for example, 6 divided by 3 gives a different answer than 3 divided by 6. Some children may recognize that division problems, such as 3 ÷ 6, can be thought of as fractions: 3 ÷ 6 is equivalent to _36 or _12 . Finding Patterns in the WHOLE-CLASS DISCUSSION Facts Table (Math Journal 1, inside front cover; Math Masters, p. 98) Algebraic Thinking Ask children to study the Multiplication/ Division Facts Table on the inside front cover of the journal. You may also display a transparency of the table (Math Masters, page 98). Give children a few minutes to examine the table. Have them describe patterns they find. Examples: Going across the second row and down the second column, the numbers increase by 1. In the third row and third column, the numbers increase by 2, and so on. In the 10-column and the 10-row, all of the numbers end in 0. In the 5-column and the 5-row, all of the numbers end in 0 or 5. In the 2-column and the 2-row, all of the numbers end in an even number. In the diagonal, moving from upper left to lower right, the numbers increase by 3, 5, 7, 9, and so on. Teaching Master Name Date Time Page Title Multiplication/Division Facts Table LESSON 40 06 䉬 Using the Facts Table and Multiplication/Division Facts Table ⫻,⫼ 1 2 3 4 5 6 7 8 9 10 1 1 2 3 4 5 6 7 8 9 10 2 2 4 6 8 10 12 14 16 18 20 3 3 6 9 12 15 18 21 24 27 30 4 4 8 12 16 20 24 28 32 36 40 5 5 10 15 20 25 30 35 40 45 50 6 6 12 18 24 30 36 42 48 54 60 7 7 14 21 28 35 42 49 56 63 70 8 8 16 24 32 40 48 56 64 72 80 9 9 18 27 36 45 54 63 72 81 90 10 10 20 30 40 50 60 70 80 90 100 WHOLE-CLASS ACTIVITY Fact Families (Student Reference Book, pp. 52 and 53) Model how to use the table to find products. Example: 5 × 7 = ? and 7 × 5 = ? ● Find the 5-row. Go across the 5-row to the 7-column. That number is 35. This shows that 5 × 7 = 35. ● Find the 7-row. Go across the 7-row to the 5-column. That number is 35. This shows that 7 × 5 = 35. Have children practice other multiplication examples, including 8 × 1 = ? and 1 × 4 = ?. Use the Multiplication/Division Facts Table to highlight the special property of 1 in multiplication. If a number is multiplied by 1, the number is not changed. 8 × 1 = 8; 1 × 4 = 4. Math Masters, p. 98 274 Unit 4 Multiplication and Division EM3cuG3TLG1_273-277_U04L06.indd 274 12/20/10 7:36 AM Next, demonstrate how to use the Multiplication/Division Facts Table to find quotients. Example: 28 ÷ 4 = ? Find the 4-row. Go across the 4-row until you find 28. Go up that column to the heading, which is 7. This also shows that 28 ÷ 4 = 7. Multiplication/Division Facts Table Find the 4-column. Go down the column until you find 28. Go across the row to the heading, which is 7. This also shows that 28 ÷ 4 = 7. Have children practice other division examples including 6 ÷ 1 = ? and 7 ÷ 7 = ?. Use the Multiplication/Division Facts Table to highlight the special property of 1 in division. If a number is divided by 1, the number is not changed. If a number is divided by itself, the result is 1. For example, 6 ÷ 1 = 6 and 7 ÷ 7 = 1. 3 ,4 1 2 3 4 5 6 7 8 9 10 1 1 2 3 4 5 6 7 8 9 10 2 2 4 6 8 10 12 14 16 18 20 3 3 6 9 12 15 18 21 24 27 30 4 4 8 12 16 20 24 28 32 36 40 5 5 10 15 20 25 30 35 40 45 50 6 6 12 18 24 30 36 42 48 54 60 7 7 14 21 28 35 42 49 56 63 70 8 8 16 24 32 40 48 56 64 72 80 9 9 18 27 36 45 54 63 72 81 90 10 10 20 30 40 50 60 70 80 90 100 Call out multiplication facts. Ask children to highlight the facts with a sheet of paper as shown in the margin. Then children state the corresponding division facts. Alternately, children highlight division facts on the table as you call them out. They then state the corresponding multiplication facts. 1 2 3 4 5 6 7 8 9 10 1 1 2 3 4 5 6 7 8 9 10 2 2 4 6 8 10 12 14 16 18 20 3 3 6 9 12 15 18 21 24 27 30 4 4 8 12 16 20 24 28 32 36 40 5 5 10 15 20 25 30 35 40 45 50 6 6 12 18 24 30 36 42 48 54 60 7 7 14 21 28 35 42 49 56 63 70 8 8 16 24 32 40 48 56 64 72 80 9 9 18 27 36 45 54 63 72 81 90 10 10 20 30 40 50 60 70 80 90 100 PARTNER ACTIVITY (Math Journal 1, Activity Sheets 1 and 2) Student Page Date Time LESSON Multiplication/Division Fact Triangles 1 46 4 2 Links to the Future 6 ⫻, ⫼ These Fact Triangles present the “easier” facts. In Unit 7, children will use the harder Fact Triangles (Activity Sheets 3 and 4). Do not expect all children to master all of the easier facts at this time. Children will have more opportunities to practice the facts in later units. 4 NOTE Have children store their Fact Triangles in their tool kits in envelopes. Some teachers have children write the fact families on the backs of the Fact Triangles. This should be an ongoing project, done a few at a time. ⫻, ⫼ Review the procedure for practicing the facts with Fact Triangles. While one child covers a number on a Fact Triangle, the partner tells the multiplication or division fact for the exposed numbers. The guide may be positioned either way to show 4 × 7 = 28, 7 × 4 = 28; or 28 ÷ 4 = 7 and 28 ÷ 7 = 4. 2 2 ⫻,⫼ 2 3 3 4 2 3 Have children cut out the Multiplication/Division Fact Triangles from Activity Sheets 1 and 2 at the back of their journals. 8 Practicing with Fact Triangles Multiplication/Division Facts Table 3 ,4 ⫻,⫼ V I S U A L ⫻, 3 9 5 20 15 ⫼ ⫻, ⫼ 12 T A C T I L E 16 10 K I N E S T H E T I C ⫻, 4 A U D I T O R Y 5 Have children practice with the Fact Triangles on Activity Sheets 3 and 4 as appropriate. ⫼ ⫻, ⫼ Adjusting the Activity 4 3 5 4 ⫻,⫼ Activity Sheet 1 Math Journal 1, Activity Sheet 1 EM3MJ1_G3_U04_79-101.indd 169 12/20/10 7:31 AM Lesson 4 6 EM3cuG3TLG1_273-277_U04L06.indd 275 275 12/20/10 7:36 AM Student Page Date Time 4 6 䉬 Write ⬍, ⬎, or ⫽. 1. 3⫻2 4⫻1 5⫻3 9⫻0 ⫽ ⬎ ⬍ ⫽ 5 ⫻ 9 ⫽ 45 9 ⫻ 5 ⫽ 45 45 ⫼ 5 ⫽ 9 45 ⫼ 9 ⫽ 5 8⫻0 5⫻4 0⫻7 yd Rule ⫻3 Write the fact family. 2. 2⫻3 Complete. 3. 13 56 yd ft 2 5 6 15 3 10 30 45 ⫻, ⫼ 9 5 55 Use the dots to show a 7-by-6 array. 4. 9 What is the number model? Answers vary. ft t 7 52 203 204 Lengths (in.) of 13 cats, including the tails: 5. 2 Ongoing Learning & Practice Math Boxes LESSON ⫻ 6 ⫽ 42 Fill in the empty frames. 6. Rule ⫹1,000 30, 29, 28, 24, 29, 35, 16, 27, 29, 36, 28, 31, 32 What is the maximum length? Fill in the oval for the best answer. 36 inches 16 inches 29 inches 30 inches 64 65 1,107 2,107 3,107 6,107 5,107 4,107 7,107 79 200 201 Practicing with ×, ÷ Fact PARTNER ACTIVITY Triangles Have partners use their Fact Triangles to practice basic multiplication and division facts. At first, children should limit themselves to finding products. That is, one partner covers the number below the large dot, and the other gives the product of the uncovered factors. When children are well on their way to learning products, they can cover one of the other two numbers to practice finding missing factors. Math Boxes 4 6 INDEPENDENT ACTIVITY (Math Journal 1, p. 90) 90 Math Journal 1, p. 90 Mixed Practice Math Boxes in this lesson are paired with Math Boxes in Lesson 4-9. The skill in Problem 6 previews Unit 5 content. Writing/Reasoning Have children answer the following question: When a number is multiplied by 1, the number does not change. What can you say about dividing a number by 1? Sample answer: When a number is divided by 1, the number does not change. Home Link 4 6 INDEPENDENT ACTIVITY (Math Masters, pp. 99–102) Home Link Master Name Date HOME LINK 40 06 䉬 Page Title PageTriangles Title ⴛ, ⴜ Fact Home Connection Children review multiplication and division fact families. Send home copies of Math Masters, pages 101 and 102, which contain Fact Triangles. Time continued Tell someone at home about multiplication/division fact families. 1. The numbers 2, 5, and 10 form the following facts: 10 2 5 10 5 2 Knowing 6 2 12 and 2 6 12 helps me know 12 2 6 and 12 6 2. 25 52 2. 10 10 3 Differentiation Options 3. The numbers 2, 7, and 14 form this multiplication/division fact family: 2 7 14 7 2 14 14 2 7 14 7 2 READINESS Practicing Multiplication Facts Write the fact family for each , Fact Triangle. 4. 5. 6. 16 , 2 60 20 2 8 16 8 2 16 16 2 8 16 8 2 5 4 5 4 20 4 5 20 20 5 4 20 4 5 10 15–30 Min with a Calculator , , 8 INDEPENDENT ACTIVITY 6 10 6 60 6 10 60 60 10 6 60 6 10 (Math Masters, p. 103) To provide experience skip counting on a calculator, have children use their calculators to complete the tables on Math Masters, page 103. Review the steps for counting by 1s on the calculator. Children can program the calculator using the following steps: Math Masters, p. 100 276 Unit 4 Multiplication and Division EM3cuG3TLG1_273-277_U04L06.indd 276 12/22/10 1:48 PM Teaching Master Name TI LESSON 46 䉬 1. Press ON/C . This clears your calculator. 3. Press . This tells the calculator to count up. One 3 Two 3s Three 3s Four 3s Five 3s Six 3s Seven 3s Eight 3s Nine 3s Ten 3s 3 6 9 12 15 18 21 24 27 30 2. Use your calculator to count by 4s. Complete the table below. 4. Press 1. This tells the calculator to count by 1s. One 4 Two 4s Three 4s Four 4s Five 4s Six 4s Seven 4s Eight 4s Nine 4s Ten 4s 4 8 12 16 20 24 28 32 36 40 3. Use your calculator to count by 6s. Complete the table below. Casio 1. Press Time 1. Use your calculator to count by 3s. Complete the table below. 2. Press 0. This is the starting number. + Date Multiplication Facts & Calculator Counts . This clears your calculator. Two 6s Three 6s Four 6s Five 6s Six 6s Seven 6s Eight 6s Nine 6s Ten 6s 6 12 18 24 30 36 42 48 54 60 4. How can counting on your calculator help you learn your 2. Press 1. This tells the calculator to count by 1. 3. Press One 6 multiplication facts? Sample answer: If I can count by 3s, I know the products to the ⫻3 facts. If I can count by any number, then I know which numbers are the products to that number’s multiplication facts. . This tells the calculator to count up. 4. Press 0. This is the starting number. Now the calculator is ready to count by 1s. Without clearing their = = key. Press the key calculators, have children press the repeatedly as the class counts together by 1s. Once they recall this routine, have them work on Math Masters, page 103. When children have completed the page, discuss how calculator counting might help them learn their facts. Have children read aloud the counts they have recorded on the master. ENRICHMENT Examining a Pattern Math Masters, p. 103 PARTNER ACTIVITY 1 2 3 15–30 Min 2 4 6 3 6 9 (Math Masters, p. 98; or Math Journal 1, inside front cover) To further explore the Multiplication/Division Facts Table, have children examine a pattern in the table. Together, they circle a number on the table. Then, they circle the number in the square above, to the right, below, and to the left of the chosen number. Next, they add the starting number plus the four circled numbers. Children record their starting number and the sum of the five circled numbers on a half-sheet of paper as shown. They repeat this several times and look for a pattern in the recorded numbers. The product of the starting number and 5 is always equal to the sum of the five numbers. Ask: How does this pattern work? Sample answer for the example: “I made the 6s into 4s and added the leftovers to the 2s to make them into 4s. So I had five 4s.” Starting Number 4 Sum of 5 Numbers 4 + 2 + 6 + 6 +2 = 20 Sample recording sheet Lesson 4 6 EM3cuG3TLG1_273-277_U04L06.indd 277 277 12/20/10 7:36 AM
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