Moving with Algebra Sampler

21 Lesson Plans 99 ©MathTeachersPress, Inc. 99 8. 2 3 5 9 – 7. 3 5 – 9 10 6. 1 2 – 7 12 5. 1 3 – 5 12 4. 3 5 – 7 10 3. 1 2 – 8 10 Subtracting Unlike Fractions Dan walked 1 1 0 of a mile to the movie. Then he walked 2 5 of a mile to the restaurant. How much farther was his walk to the restaurant than to the movie? Thisproblem comparestwo numbers,so it is a subtraction problem. Change fractionsto a common denominator. 2 5 1 10 1 10 4 10 3 10 x 2 x 2 – mile = = 9. A recipe for cookies calls for 2 3 cup of brown sugar and 1 2 cup of white sugar.How much of both sugars is needed? __________ 10. Carol jogged 3 8 of a mile in the morning and 3 4 of a mile in the afternoon.How much farther did she jog in the afternoon? __________ 1. 5 6 3 4 – 2. 7 8 1 4 – A B C D 4 4 1 2 3 8 4 32 5 8 1 4 – = Eat at Joe’s! 1 1 0 mile 2 5 mile Solve. 1 12 3 10 1 12 1 12 3 10 1 10 58 1 9 1 1 cup 6 3 mi. 8 Objective: To subtract fractions with unlike denominators. Materials: Fraction Bars ® , multiple strips (made from the Multiplication Table (Master 6), 10-sided dice Subtraction with Fraction Bars Write on the board: You buy 3 4 yard of fabric. You use 1 3 yard to make a pillow. How much do you have left? You live 1 9 0 kilometer from school. You walk 1 2 kilometer. How far are you from school? Demonstrate the solution to each problem with Fraction Bars ® and multiple strips. Each small group will need a set of fraction bars and a Multiplication Table (Master 6) cut into multiple strips. Remember the Golden Rule of fractions. You cannot add or subtract fractions unless they are the same color. Find 3 ⁄ 4 and 1 ⁄ 3 . Are they the same color? (No) What color can they be changed to? (orange) For problem 1 change the blue 3 ⁄ 4 bar into orange 9 ⁄ 12 and the yellow 1 ⁄ 3 bar to orange 4 ⁄ 12 . To show the same problem with multiple strips, place the 3 multiple strip over the 4 strip and the 1 strip over the 3 strip. Write on the board: 1 9 2 – 1 4 2 = 1 5 2 For problem 2, change 1 ⁄ 2 green to 5 ⁄ 10 white and then subtract: 9 ⁄ 10 – 5 ⁄ 10 = 4 ⁄ 10 . The fraction 4 ⁄ 10 may be simplified to 2 ⁄ 5 . Direct attention to the top of the page. Demonstrate the solution with multiple strips. Students may use fraction bars or multiple strips to complete the rest of the page. Dicey Differences Game for 2 players. Players take turns throwing two 10-sided dice twice and forming a fraction each time using the smaller number for the numerator and the larger number for the denominator. The player with the greater difference between his or her fractions earns one point. For example, a player throwing a 1 and a 6 on the first throw and a 2 and a 3 on the second throw would subtract: 2 ⁄ 3 – 1 ⁄ 6 for a difference of 1 ⁄ 2 . Authoring Word Problems Continue developing a class file of word problems by having students author at least one addition problem and one subtraction problem that might be solved by a computation problem from pages 98–100. Suggest common settings for the problems, e.g., cooking, map directions, capacity. Encourage students to write problems about their real world. Skill Builders pp. 80, 81 (6NS 2.1, 7NS 1.2) Multiplying Fractions Fractions Finding the pattern for multiplying fractions Sample Lesson Fractions Unit 2