The traditional method of subtracting, borrowing and carrying numbers, is derisively called the “Granny Method.” The new method makes no freaking sense to either my third grader or my wife.
We send our child to a Christian private school. We thought our child could escape this madness. But standardized tests, the SAT, and the ACT are all moving over to Common Core. So our child has to learn this insanity.
Parents and kids feel helpless, writes Erickson. And, in his wife’s case, homicidal.
Alternatives such as “counting up” are supposed to supplement traditional methods, not replace them, responds Andy Kiersz at Business Insider. Common Core’s fourth-grade standards say students should “fluently add and subtract multidigit whole numbers using the standard algorithm.”
The “counting up” method . . . captures some of the underlying aspects of subtraction and place value that allow borrowing and carrying to work.
. . . The student starts counting by ones from the smaller number up to the nearest multiple of 10. Then she counts by 10s to 100, then by hundreds to the first digit of the larger number, then takes the remaining two-digit part of the larger number. These are all just a different way of subtracting in different place values. Adding these intermediate steps together, the student gets her result.
The point of these alternative methods is to provide a different perspective on a problem, which is often useful in learning math at any level.
Ideally, these alternatives build students’ understanding of key concepts,” making it easier for them to work with the standard algorithms later,” writes Kiersz.
Ideally, perhaps. What does it do in reality?