Mathematical Pedagogy #1
Before you watch the number talk for 65+19 in a first-grade class, think about how you would mentally solve this problem. Write down your own strategy to solve it:
1) Your solution strategy for mentally solving 65+19:
I would start to solve this problem mentally, by first mentally stacking the two numbers and starting on the left. I would mentally picture only the 9 and the 5 and proceeded to add them together (9+5=14). Once I came to the conclusion that the answer was fourteen, I then moved the left side of the problem and added together 6+1+1. After that, I simply put together the two answers and came to the conclusion that the answer is 84.
2) Write down the solution strategies that students generated for 65+19. Explain how are students using number relationships or decomposing the numbers to solve the problem?
The first student came to the solution that 65+19=84. He proceeded to tell the teacher and his classmates that he came to this solution by first adding ten to sixty-five (65+10=75), but he knows that he still needs to add nine. He then decided to add five to seventy-five, so that …show more content…
They did this by decomposing the multi-digit numbers they were given to add together into multiples of ten, so that it could be easier for them to add. When they could not make a remaining number into a multiple of ten, they did the next best thing and made it, so they used fives to break down the equation. For example, one student chose to decompose the problem to make it, so they were able to add easily, by subtracting one from sixty-five in order to make nineteen turn into twenty. Other students performed this strategy by subtracting five from sixty-five in order to make sixty. These students have used their understandings of numbers, their relationships, and the concept of decomposing as an effort to be more efficient when trying to solve a mathematical