Texas Instruments TI-34 II Teachers Guide - Page 38

Sewing Costumes-Fractions Overview Students will use the fraction capability of the TI-34 Û calculator to determine if enough material is available to make a given number of costumes. They will also determine how much more is needed or how much extra they have. Math Concepts • multiplying mixed numbers by whole numbers • subtracting mixed numbers Materials • TI-34 Û • pencil • student activity (page 34) Introduction Set up the activity by discussing the concepts of multiplying mixed numbers by whole numbers, and subtracting mixed numbers. 1. Have students practice multiplying mixed numbers by whole numbers (and simplifying where necessary): a. 3 3/5 x 7 b. 9 7/8 x 4 c. 4 1/7 x 5 d. 7 4/5 x 3 25 1/5 39 1/2 20 5/7 23 2/5 2. Have students practice subtracting mixed numbers. a. 4 5/8 - 3 4/5 b. 9 7/8 - 6 3/4 c. 5 5/6 - 3 1/9 d. 8 1/3 - 7 4/7 33/40 3 1/8 2 13/18 16/21 Activity Present the following problem to students: You are sewing costumes for a dance festival. Each costume takes 2 3/8 yards of material. You have 23 yards to make 14 costumes. Do you have enough? If you do, do you have any extra? How much? Do you need more? How much? If the material cost $3.98 per yard, how much will it cost to buy the additional material? How many costumes could you make with the material you have? What if each costume only required 1 2/3 yards? Would you have enough? ³ Be sure that the calculator is in mixed-number mode by pressing % ~ and pressing " or ! to select the mixed number mode. A−bÌc d/e ³ To enter the first problem, press 3 @ 3 > 5 V 7