Challenge 4

Derek: He adds and subtracts numbers using a strategy that allows him to do the math in his head. He breaks the numbers down in order to make it easier to figure out in his head. The word problem was more difficult for him because he had to think about what numbers to use and what operation to do instead of solving a simple problem (8+7). Once he figured that out, he came across the answer the same way as before.

Elizabeth: She understands adding doubles and then subtracting the extra to get the answer. She uses her fingers to figure out answers and pretends that there are extra fingers when the number is more than 10 to help her find the answer. She uses sequences of 5 and 10, such as when she is adding and subtracting the cows, which shows that she understands number concepts as well as the operations.

Jim: He has some trouble counting backwards for subtraction, but he is able to use sequences of 5 and 10 for both addition and subtraction (12-5, 5+5 is 10 and 2 more is 12 so the answer is 7). He He can add doubles and then subtract and/or add numbers from the answer in order to get the answer to the problem (7+8, 7+7 is 14 so one more is 15).

Lauren: She understands adding doubles and then subtracting the extra to get the answer. She uses her fingers when explaining how she got her answer to the teacher but does not need to use her fingers to count while she is adding or subtracting. She easily solves problems, whether they are simple operation problems or word/story problems, showing that she understands number concepts well.