Making Number Talks Matter * Grades 4-10 Cathy Humphreys and Ruth Parker SUBTRACTION Chapter 4 pages 37-57 minuend - subtrahend = difference Round the subtrahend Decompose the to a multiple of 10 and Add instead. Same Difference Break apart by place. subtrahend. adjust. pages 39, 45 pages 40, 47 pages 41, 50 pages 38, 44 pages 38, 41 13 – 9 32 – 6 23 – 19 93 – 28 72 – 56 24 - 8 21 – 8 51 – 48 76 – 39 81 – 27 61 – 8 13 – 7 34 – 27 57 – 18 63 – 28 43 – 9 43 – 7 223 – 219 236 – 188 337 - 159 44 – 8 351 – 348 3456 - 687 63 - 28 5.7 – 2.9 61 - 7 435 - 427 71 – 39 8.42 – 0.17 9.3 – 2.8 84 – 59 13.23 – 8.54 43 – 17 5.14 – 4.6 7.6 – 3.9 42 – 19 5.75 – 1.85 4.1 – 2.03 62 – 16 2 - 0.7 50 – 28 0.236 – 0.188 47 – 28 3.4 – 1.25 QUESTIONS: 134 – 99 83 – 37 9.15 – 7.5 Did you think about it as 6 minus 3 or 600-300? 247 -98 91 – 26 How do you know 315 – 97 84 - 36 that 30 minus 70 is 468 – 99 QUESTIONS: negative 40? How did you decide what 3.63 – 1.95 to take away? 3.6 – 1.95 QUESTIONS: Why did you want to 3.63 – 1.9 How did you decide your break the numbers apart? first move? Did anyone break the Did anybody use this subtrahend apart in a QUESTIONS: strategy but make different way? How do you know the different jumps? distance is the same QUESTIONS: How do you know what between the numbers? the answer is? Why did you take [200] Why did you shift to away instead of [198]? ____? Did you take away too Did anyone use this same many or too few? strategy in a different Why did you add [2] way? twice?
Making Number Talks Matter * Grades 4-10 Cathy Humphreys and Ruth Parker SUBTRACTION Chapter 4 pages 37-57 minuend - subtrahend = difference Round the subtrahend to a multiple of 10 and adjust. pages 38, 41 Decompose the subtrahend. pages 38, 44 Add instead. pages 39, 45 Same Difference pages 40, 47 Break apart by place. pages 41, 50 13 – 9 24 - 8 61 – 8 43 – 9 32 – 6 21 – 8 13 – 7 43 – 7 44 – 8 61 - 7 23 – 19 51 – 48 34 – 27 93 – 28 76 – 39 57 – 18 236 – 188 3456 - 687 72 – 56 81 – 27 63 – 28 337 - 159 223 – 219 351 – 348 435 - 427 63 - 28 71 – 39 84 – 59 42 – 19 50 – 28 5.7 – 2.9 8.42 – 0.17 13.23 – 8.54 4.1 – 2.03 9.3 – 2.8 7.6 – 3.9 5.75 – 1.85 0.236 – 0.188 43 – 17 62 – 16 47 – 28 83 – 37 91 – 26 84 - 36 5.14 – 4.6 2 - 0.7 3.4 – 1.25 9.15 – 7.5 QUESTIONS: Did you think about it as 6 minus 3 or 600-300? How do you know that 30 minus 70 is negative 40? 134 – 99 247 -98 315 – 97 468 – 99 QUESTIONS: How did you decide what to take away? Why did you want to break the numbers apart? Did anyone break the subtrahend apart in a different way? 3.63 – 1.95 3.6 – 1.95 3.63 – 1.9 QUESTIONS: How did you decide your first move? Did anybody use this strategy but make different jumps? How do you know what the answer is? QUESTIONS: How do you know the distance is the same between the numbers? Why did you shift to ____? Did anyone use this same strategy in a different way? QUESTIONS: Why did you take [200] away instead of [198]? Did you take away too many or too few? Why did you add [2] twice?