Comparing and Ordering Fractions Analyzing Elections SUGGESTED LEARNING STRATEGIES: Marking the Text, Summarize/Paraphrase/Retell, Create Representations, Vocabulary Organizer ACTIVITY 1.5 My Notes • Comparing and ordering fractions with like and unlike denominators and numerators • Writing equivalent fractions Materials • Number cubes • Fraction strips/circles (optional) • Colored paper (optional) 1. Work together to simulate this election. a. In your group, roll a number cube until you have 23 votes. Organize your data in this table. Chunking the Activity #1–3 #4–5 Answers may vary. Sample answers shown. Betty (2) Carla (3) Deon (4) Total Votes 4 8 7 4 23 Comparing and Ordering Fractions Activity Focus Every West Middle School homeroom must elect a student council representative. Since Mr. Fare’s homeroom students do not know each other yet, he has asked interested students to volunteer. Andy, Betty, Carla, and Deon decide to volunteer. To simulate a regular election, each of the 23 students in his homeroom will roll a number cube to vote. A 1 is a vote for Andy. A 2 is a vote for Betty. A 3 is a vote for Carla. A 4 is a vote for Deon. If 5 or 6 is rolled, the student continues to roll until 1, 2, 3, or 4 is rolled. Andy (1) ACTIVITY 1.5 Investigative #6–8 #9 #10–15 #16 #17 #18 Introduction Marking the Text, Summarize/Paraphrase/Retell b. Who did your group elect as the homeroom representative? 12 Create Representations, Answers may vary. Sample answer: Betty Debriefing Check that each group of students is correctly collecting data. You may need to discuss what occurs when students roll a 5 or 6. Students use the last column in the table to ensure that their group counted 23 votes. A class discussion following 1b may include a short explanation of the possibility of a tie. © 2010 College Board. All rights reserved. 2. List the names of the candidates in order of most to least number of votes. Next to each name, write the number of votes he or she received. Answers may vary. Sample answer: Betty 8 Carla 7 Andy 4 Deon 4 3. What fraction of the total votes did each candidate receive? Write the fractions in order from greatest to least. 8 Answers may vary. Sample answer: Betty ___ 23 7 Carla ___ 23 4 ___ Andy 23 4 Deon ___ 23 MATH TERMS The number of votes each candidate received can be written as a fraction or as a ratio of the number of votes received to the total number of votes. These ratios are called rational numbers. 3 Use this question to check Unit 1 • Number Concepts © 2010 College Board. All rights reserved. 025-032_SB_MS1_1-5_SE.indd 25 25 12/16/09 5:43:49 PM TThe Math Terms box has an informal description of rational n numbers. The actual definition of a rational number is a p number ex expressed as __ q, where p and q are integers and q is not zero. TEACHER TO TEACHER that students understand what the numerator and denominator in each fraction mean. Students may use the table instead of the fractions to find their answers. Be certain that the connection between the numbers of votes, from most to fewest, and the fractions of the total votes, from greatest to least, is established. If possible, discuss student answers that reflect both the table and the fraction methods. Unit 1 • Number Concepts 25 4 Marking the Text Check to see that students understand how to order fractions with a given common denominator. ACTIVITY 1.5 continued Comparing and Ordering Fractions Analyzing Elections SUGGESTED LEARNING STRATEGIES: Marking the Text, Quickwrite My Notes 5 of the 4. In the election in Mr. Fare’s homeroom, Andy received ___ 23 7 8 of total votes, Betty received ___ of the total, Carla received ___ 23 23 3 of the total. Who was elected? the total, and Deon received ___ 23 5 Quickwrite, Guess and Check This question allows students to understand the need to use a common denominator to compare fractions. Before continuing, you may ask students to quickly make a prediction of who won the election. Point out that they are using the Guess and Check strategy and will check their answers later. Carla The 300 students at West Middle School held a traditional election for student council officers. Eden, Frank, Gabrielle, and Hernando ran for president. 3 of the votes, 4 of the votes, Frank received ___ 5. Eden received ___ 15 1 10 2 of Gabrielle received ___ of the votes, and Hernando received __ 5 30 the votes. Why is it more difficult to decide who won this election than it was for the election in Question 4? 6 A common fractional unit is the unit fraction of which each fraction is composed. For example, _27_ and _57_ are both composed of sevenths, so the common fractional unit is _17_. The fractions do not have a common denominator. To make it easier to compare the results from this election, you can rewrite these fractions as equivalent fractions with a common denominator. 6. What common denominator do all the fractions in Question 4 share? 7 Activating Prior Knowledge, Create Representations This question is intended to activate students’ prior knowledge of writing equivalent fractions by making drawings. © 2010 College Board. All rights reserved. ACTIVITY 1.5 Continued The common denominator is 23. The LCD is simply the LCM for two or more different denominators. The LCM of 6 and 8 is 24, so you use 24 as the LCD to write 1. 1 and __ equivalent fractions for __ 8 6 7. You can draw a model to compare fractions. Use this method to 3 of the votes to Hernando’s __ 2 of the votes. compare Frank’s ___ 5 10 a. What is the least common denominator, or LCD, of these two fractions? (Hint: Look for the least common multiple, or LCM, of 5 and 10.) The LCD is 10. 26 SpringBoard® Mathematics with Meaning™ Level 1 12/16/09 5:43:57 P 0 © 2010 College Board. All rights reserved. 025-032_SB_MS1_1-5_SE.indd 26 26 SpringBoard® Mathematics with Meaning™ Level 1 Comparing and Ordering Fractions ACTIVITY 1.5 Analyzing Elections continued 7 (continued) Part e serves as SUGGESTED LEARNING STRATEGIES: Create Representations, Quickwrite, Self Revision/Peer Revision, Think Aloud, Summarize/ Paraphrase/Retell, Vocabulary Organizer a review of writing inequality expressions using symbolic notation. Be sure to point out the Writing Math signal box to students, as many will need a review on what the symbols mean. My Notes b. Draw a rectangle in the My Notes space. Then divide it into the number of equal parts you found in Part a. 2. c. Shade your rectangle to represent __ 5 2. d. Write an equivalent fraction for __ 5 4 __2 = ___ 5 8 Quickwrite, Self Revision/ Peer Revision, Debriefing This question leads students to finding a common denominator for all four fractions, so that they can compare all of them at once. Part b gives students a reason for finding a more efficient method for comparing fractions than making drawings. 10 2 to write an inequality e. Use the equivalent fraction for __ 5 comparing the votes for Frank and Hernando. Who received more votes? 3 ; Hernando received more votes. 4 > ___ ___ 10 10 8. Next compare the votes for Eden and Gabrielle. a. Can you use 10 as the common denominator to compare their votes? Explain your reasoning. WRITING MATH The symbols <, >, ≤, and ≥ are inequality symbols. Remember, each symbol opens towards the greater number and points to the smaller number: 5 > 1. Answers may vary. Sample answer: No, because neither 30 nor 15 is a factor of 10. Paragraphs Think Aloud, Summarize/Paraphrase/Retell, Vocabulary Organizer b. One way to compare all four students’ votes is to find how many of the 300 votes each candidate received. Would you want to draw a model to do this? Why or why not? © 2010 College Board. All rights reserved. Answers may vary. Sample answer: You could, however, it would be difficult to draw rectangles cut into 300 equal pieces. The numbers are too big for accurate sketches. You can use the Property of One to find equivalent fractions. 3, 2 , __ When you use the Property of One, you multiply a fraction by __ 4 , and so on. This is the same as multiplying the fraction by the2 3 __ 4 3 , __ 4 , describes the number 1 in 2 , __ number 1. Each of the fractions, __ 2 3 4 a different way. 1 , you To use the Property of One to find an equivalent fraction for __ 2 multiply this way. 3 = _____ 1 × 3 = __ 3 1 = __ 1 × 1 = __ 1 × __ __ 2 2 2 3 2×3 6 1 are each Notice that the numerator and denominator of __ 2 multiplied by 3. MATH TERMS The Property of One for fractions states that if the numerator and the denominator of a fraction are multiplied by the same number, its value is not changed. Unit 1 • Number Concepts PM 025-032_SB_MS1_1-5_SE.indd 27 © 2010 College Board. All rights reserved. ACTIVITY 1.5 Continued 27 12/16/09 5:44:00 PM MINI-LESSON: Finding Equivalent Fractions Use five strips of different colored paper, all of the same length. Fold one strip into halves, one into thirds, one into fourths, and one into sixths. (To form sixths, fold into thirds, then fold each third in half.) Leave one strip unfolded to represent the number 1. Have students match the strips to help rename the fractions, draw a sketch of their strips, and complete the fraction for each problem below. 1 = __ 2 a. __ 3 6 1 = __ 2 b. __ 4 2 3 1 = __ c. __ 2 6 6 3 4 = __ 2=1 d. __ = __ = __ 4 6 3 2 Unit 1 • Number Concepts 27 ACTIVITY 1.5 continued Comparing and Ordering Fractions Analyzing Elections 9 Think/Pair/Share This question b b SUGGESTED LEARNING STRATEGIES: Think/Pair/Share, Simplify the Problem, Quickwrite, Self Revision/Peer Revision My Notes 9. Use the Property of One to rename all four fractions to find the fraction of the 300 total votes each student received. 4 = ____ ___ 80 15 300 b. Frank 3 = ____ 90 ___ 10 300 c. Gabrielle 1 = ____ 10 ___ 30 300 2 = ____ 120 __ 5 300 d. Hernando b b×n a×n other words, the fraction _____ is b×n a_ _ equivalent to the fraction . b 10. Compare the renamed fractions. Then list the original fractions from least to greatest. 3 , __ 4 , ___ 2 1 , ___ ___ 30 15 10 5 Students may not be ready to understand this explanation that uses variables as the numerator and denominator, but this question gives them an opportunity to work with the Property of One on some specific numerical examples. Now explore some ideas about common denominators. 11. You changed each fraction to an equivalent fraction with a common denominator of 300. Why did this make it easier to compare the fractions of the total votes for each candidate? Once the denominators are the same, you can simply compare the numerators. 12. List other common denominators that could be used to write equivalent fractions for comparing the presidential election votes at West Middle School. 0 Guess and Check Check student guesses from Question 5. Answers may vary. Possible common denominators are 30, 60, 90, 120, 150, 180, 210, 240, 270, 330, 360, … a Simplify the Problem, Quickwrite, Self Revision/Peer Revision Students see a need for finding common denominators. bd Simplify the Problem, Quickwrite, Self Revision/ Peer Revision In Question 12, students list as many other common denominators as they can find, leading to a discussion in Question 13 about the least common denominator. Be sure to elicit this term if the students do not, and ask students to use either their Math Notebooks or a vocabulary organizer to add it to their list of terms. Discuss how to find the LCD and if it is important to use it instead of a different common denominator. a. Eden © 2010 College Board. All rights reserved. requires students to use the Property of One. The Property of One states that any fraction __a can b be expressed by a different yet equivalent fraction by multiplying by an appropriate representation of the number 1. The number 1 can be represented in fraction form as _nn_. The Property of One says that a×n _a_ = _a_ × 1 = _a_ × _n_ = _____ . In n 13. Choose one of the common denominators you listed in Question 12 that you think may be easier to work with than 300 to compare the fractions. Explain your choice. Answers may vary. Sample answer: I chose 30 as the common denominator, as it is easier to work with smaller numbers. 14. Change each fraction from Question 9 to an equivalent fraction with the denominator you chose in Question 13. Answers may vary. Sample answer: 8 , ___ 3 = ___ 9 , ___ 4 = ___ 1 = ___ 1 , __ 2 = ___ 12 ___ 15 30 10 30 30 30 5 30 28 SpringBoard® Mathematics with Meaning™ Level 1 025-032_SB_MS1_1-5_SE.indd 28 12/16/09 5:44:04 P 0 Suggested Assignment CHECK YOUR UNDERSTANDING p. 32, #1–5 UNIT 1 PRACTICE p. 58, #31–34 Often it helps students to understand the Property of One if they draw a 1 around the fraction as they multiply. For example: TEACHER TO TEACHER 2_ = __ 2 _1_ × ___ __ 3 2 6 28 SpringBoard® Mathematics with Meaning™ Level 1 © 2010 College Board. All rights reserved. ACTIVITY 1.5 Continued Comparing and Ordering Fractions ACTIVITY 1.5 Analyzing Elections continued e Debriefing SUGGESTED LEARNING STRATEGIES: Create Representations, Look for a Pattern My Notes Fraction of Votes Eden 4 ___ Frank Gabrielle Hernando Fraction Fraction Final Rank in (Denominator of 300) (Denominator You Chose) Election (1st–4th) 15 3 ___ 10 1 ___ 30 2 __ 5 80 ____ 8 ___ 300 30 90 ____ 9 ___ 300 30 10 ____ 1 ___ 300 30 120 ____ 12 ___ 3 EXAMPLE 1 Debriefing Now that students understand the Property of One, they apply this knowledge to look for ways to make this method even more efficient when comparing two fractions at a time. When students find a common denominator by multiplying the two given denominators, they are multiplying one denominator by the other. 2 4 1 30 300 16. Explain how you determined the final ranking. Answers may vary. Sample answer: I used the numerators. Two ways to compare fractions are to rewrite the fractions using a common denominator or to use cross products. You do not have to find the LCD to write equivalent fractions. You can always find a common denominator by multiplying the denominators of the fractions. EXAMPLE 1 5. 4 and ___ Compare __ 5 4 ? ___ __ Step 1: 9 × 11 = 99 © 2010 College Board. All rights reserved. 9 11 Using a common denominator: Step 2: Step 3: Multiply the denominators to find a common denominator. Write equivalent fractions. Compare the fractions. 9 11 Thus, as they use the Property of One, they are also multiplying each numerator by the denominator of the other fraction. When fractions have common denominators, only the numerators must be compared. By only finding the numerators, the students can save time when comparing. 5 = ___ 45 4 = ___ 44 and ___ __ 9 99 11 99 45 , so __ 5 44 < ___ 4 < ___ ___ 99 99 9 11 Using cross products: Step 1: Compare the products found by multiplying the numerator of one fraction by the denominator of the other fraction. 4 × 11 = 44 4 __ 5 × 9 = 45 5 ___ Many teachers refer to cross products as “cross-multiplication.” It is important that students see this pattern and understand why cross-multiplication works as a method for comparing before they are allowed to use it. 9 11 5 4 < ___ 44 < 45, so __ 9 11 TRY THESE A 3. 2 and __ a. Compare __ 7 9 5 __ ___ b. Compare and 7 . 9 13 5 > ___ 3 , b. __ 2 < __ 7 a. __ 9 7 9 13 Unit 1 • Number Concepts PM 025-032_SB_MS1_1-5_SE.indd 29 © 2010 College Board. All rights reserved. A After Question 15 is a g good place for additional practice w with using common denominators to compare and order fractions. TEACHER TO TEACHER 15. Use this table to organize your data for the election results. Candidate ACTIVITY 1.5 Continued 29 12/16/09 5:44:06 PM MINI-LESSON: Understanding the Property of One If students are struggling with the Property of One and why it works, use the following guided questioning. • By what number can you multiply another number without changing the value of the other number? • By what number can I multiply 5 in order to get 5? • Give five examples of this. • Will this work with fractions and decimals too? Give an example. • How many different ways can you write 1 using fractions? • What does it mean to write an equivalent fraction? 1 of a pizza, is that more, less, or the same as eating __ 2 of it? • If you eat __ 4 2 Unit 1 • Number Concepts 29 ACTIVITY 1.5 continued Comparing and Ordering Fractions Analyzing Elections Connect to History Compare the fractions of votes received by the candidates in the 1860 presidential election. List the order, from most to fewest votes, in which the candidates placed. SUGGESTED LEARNING STRATEGIES: Identify a Subtask, Simplify the Problem, Create Representations My Notes As president of the Student Council, Hernando wants to speak with all the student groups about their concerns. The guidance counselor gave Hernando the following data: 8 • ___ 15 of the students take part in music. 1 of the students are in the art club. • __ 6 ___ • 16 33 of the students participate in sports. 4 of the students are in academic clubs. • __ 9 Stephen A. Douglas: 1,382,713 ________ 4,689,568 John C. Breckinridge: 212,089 ________ 1,172,392 Hernando decides to speak first with the groups that have the most participants. To do so he must order these fractions. He knows that a common denominator for them would be very large, so he asks his math teacher, Ms. Germain, if there is an easier way to order the fractions. 1,865,593 Abraham Lincoln: ________ 4,689,568 296,453 John Bell: ________ 2,344,784 17. Ms. Germain decides to explain the concept with less complicated fractions. She starts by asking Hernando to represent each of these unit fractions. g Identify a Subtask, Simplify the Problem, Create Representations (a, b), Group Presentation (b) This question introduces students to using common numerators to compare fractions. Additionally, this method reinforces the relationship between numerator and denominator. Before beginning, you might ask students to find the common denominator for these four fractions (26,730 is a common denominator; the LCD is 990) so that they can appreciate Hernando’s conclusion that the common denominator is, indeed, a very large number. Part b is a good question to use the group presentation strategy. a. Shade each rectangle to show the fraction. 1 3 © 2010 College Board. All rights reserved. ACTIVITY 1.5 Continued 1 4 1 2 1 5 b. She tells Hernando that he can also use number lines to compare the fractions. Graph each fraction on the number lines below. 1 3 1 4 0 1 0 1 1 2 1 5 0 1 0 1 30 SpringBoard® Mathematics with Meaning™ Level 1 H Help students understand why it is not mathematically aaccurate to shade a number line from zero to the given fraction This T is a misconception about graphing on a number line fraction. that may confuse students later on when they graph inequalities. Shading includes all points along the shading. Students should place only one point on each number line. TEACHER TO TEACHER 30 SpringBoard® Mathematics with Meaning™ Level 1 12/16/09 5:44:11 P 0 © 2010 College Board. All rights reserved. 025-032_SB_MS1_1-5_SE.indd 30 Comparing and Ordering Fractions ACTIVITY 1.5 Analyzing Elections continued SUGGESTED LEARNING STRATEGIES: Quickwrite, Self Revision/ Peer Revision, Questioning the Text, Identify a Subtask, Create Representations Differentiating Instruction Using concrete objects, such as breakfast bars, may help students to understand that the more parts a whole is divided into, the smaller each part is. So, the more people you share something with, the smaller the piece of it you will get for yourself. My Notes 1, 1 , __ c. Use your work from Parts a and b to order the fractions __ 3 4 1 from greatest to least. 1 , and __ __ 5 2 __1 , __1 , __1 , __1 2 3 4 5 d. Each of the four fractions you just ordered has the same numerator. Tell Hernando how he can use just the denominators to order the fractions. Answers may vary. Sample answer: When the numerators are the same, the fraction with the smallest denominator will be the largest fraction. g (continued ) Quickwrite, Self Revision/Peer Revision (d) 4 , and ___ 4 , ___ 4 , __ 4 from e. Use mental math to order the fractions __ 5 11 7 25 greatest to least. 4 , ___ 4 __4 , __4 , ___ 5 7 11 25 Hernando can see that the fractions he wants to order do not have either a common numerator or a common denominator. You may recall that mental math is working a problem in your head without writing it on paper. 18. He thinks that it will be easier to find a common numerator for them rather than a common denominator. © 2010 College Board. All rights reserved. 8 , __ 1, a. What is the least common numerator of the fractions ___ 15 6 16 4? ___, and __ 33 9 CHECK YOUR UNDERSTANDING p. 32, #5–9 b. Change each of the fractions above to an equivalent fraction with the common numerator found in Part a. 16 , __ 16 , ___ 16 = ___ 16 , __ 16 8 = ___ 1 = ___ 4 = ___ ___ 30 6 96 33 33 9 36 UNIT 1 PRACTICE p. 58, #35–39 c. Order the fractions in Part b from least to greatest using the number line below. 1 6 0 4 9 h Question the Text, Identify a Subtask, Create Representations (c), Debriefing This is a good question for questioning the text by either the student or the teacher. Ask students why Hernando thinks that finding a common numerator would be easier. Suggested Assignment 16 15 ACTIVITY 1.5 Continued 8 15 16 33 1 d. In what order will Hernando talk with the student groups? music, sports, academic clubs, art club Unit 1 • Number Concepts © 2010 College Board. All rights reserved. PM 025-032_SB_MS1_1-5_SE.indd 31 31 12/16/09 5:44:15 PM MINI-LESSON: Comparing Fractions Ask pairs of students to create a set of fraction cards. Students then play Try to Get the Whole Deck as an engaging way to practice comparing fractions. They can use the methods they learned in Example 1. Each player lays a card down and whoever has the greater fraction wins the two cards. Play continues until one player has won the entire deck. Use this time to re-teach in a small group those students who were struggling with comparing fractions. Unit 1 • Number Concepts 31 ACTIVITY 1.5 Continued Comparing and Ordering Fractions ACTIVITY 1.5 continued Analyzing Elections Answer Key 2. CHECK YOUR UNDERSTANDING Write your answers answers on on notebook notebook paper. paper.Show your work. 6. Your school is holding a mock election for Show your work. president. 250 students vote. 1. A jar is filled with 70 centimeter cubes. There are 15 red, 9 green, 21 yellow, 20 purple, and 5 orange. Write the fractions for each color in order from least to greatest. 2. Draw and shade rectangles and then order the fractions from greatest to least. 3 __ 7 , __ __ ,1 8 4 2 3a. 18 5 15 7 = ___ 14 and __ b. __ = ___ 9 18 6 18 5 c. __ 6 4. Answers may vary. Sample answer: An LCD is simply an LCM for 2 or more different denominators. 5. Player 1 10 of the total votes. Candidate 1 receives ___ 50 9 of the total votes. Candidate 2 receives ___ 25 4 of the total votes. Candidate 3 receives ___ 10 5 of the total votes. Candidate 4 receives ____ 125 Rank the candidates by the number of votes each received, from least to greatest. 3 __ 4 1 __ 2 7 __ 8 7 and __ 5. 3. Consider the fractions __ 9 6 a. What is the LCD for these fractions? b. Use the LCD you just found and the Property of One to write equivalent 5. 7 and __ fractions for __ 9 6 c. Which fraction is greater? 6. Candidate 4, Candidate 1, Candidate 2, Candidate 3 4. What is the difference between an LCD and an LCM? 7. Computer games, play sports, watch TV, read. Explanations may vary. Sample answer: Since the numerators are the same, I can compare the denominators. The larger the denominator, the smaller the fraction. 5. Two students are playing a game with fraction cards. Each player lays a card down and whoever has the greater amount wins the two cards. Who wins this pair? 7. The table below shows the fraction of students who voted for each after-school activity. Use mental math to order the activities from most popular to least popular. Explain your thinking. Computer Games 1 __ 2 Read 1 ___ 12 Watch TV 1 __ 6 Play Sports 1 __ 4 © 2010 College Board. All rights reserved. 5 9 15 1. orange ___ , green ___ , red ___ , 70 70 70 20 21 ___ ___ purple 70 , yellow 70 8. Use common numerators to compare the weekly growth of the plant. In which week did the plant grow the most? Explain how you reached your conclusion. Week 1 Player 1 Player 2 2 11 14 3 4 3 Growth (in.) 3 ___ 11 6 __ 7 12 ___ 13 9. MATHEMATICAL Describe the steps for R E F L E C T I O N comparing and ordering fractions with unlike denominators. 3 12 = ___ 8. Week 1: ___ 11 44 6 12 Week 2: __ = ___ 7 14 The plant grew the most in Week 3. 32 SpringBoard® Mathematics with Meaning™ Level 1 025-032_SB_MS1_1-5_SE.indd 32 9. Answers may vary. Sample answer: Start by making either the numerators or the denominators the same so that you can compare the fractions. To do this, find a common denominator or common numerator and use it to write equivalent fractions. If you use common denominators, compare the numerators— the greater the numerator, the greater the fraction. If you use common numerators, compare the denominators—the smaller the denominator, the greater the fraction. 32 SpringBoard® Mathematics with Meaning™ Level 1 12/16/09 5:44:19 P © 2010 College Board. All rights reserved. 12 Week 3: ___ 13
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