2+2 = ???

July 19, 2007

Actually, I know you know the answer, but I want to know how you got it. This year we are going to take part in an awesome new math program (new books and everything)! I was taking a look at some of our ideas from the first investigation (which is like a chapter, but doesn’t the word “investigation” sound cool???) and the content focuses on students explaining their answers.

I really like the idea of students explaining their answers because when I was in 5th grade, I ‘m not sure that I could. As a result, I want to see how people think about a typical addition problem.  Please let me know how you solve the following:

2,345 + 487

This is what I think:

2,345 + 487 =

2,345 + 400 = 2,745

2,745 + 80 =  2,825

2,825 + 7 = 2,832

I like to break 487 down into easier parts to manage. I look at 487 as 400+80+7. From there it is easier to add those numbers to 2,345. In order to understand this problem in this way, it is important to realize place value. In other words, 487 has 4 hundreds (400), 8 tens (80) and 7 ones (7). What do you think about this explanation? Would you do this problem this way?