The latest controversy over the Common Core education standards involves a new approach to subtraction that conservatives say is unfairly replacing tried and true methods of basic maths.
A new way to teach elementary school students multiplication is causing also some controversy — but it may be easier than the method you probably learned in school.
You probably learned multiplication through the longform method that involves “carrying” over different digits. These days, many elementary school students learn to multiply using the “box method.”
NPR demonstrated the “box method” by having a fourth grader explain how to multiply 7 by 23. We first saw this video in a Daily Caller story that criticised it.
Here’s how the “box method” works:
First you divide the larger number into its separate parts. Here, 23 becomes 20 and 3.
Next, you multiply each separate part — 20 x 7 and 3 x 7.
Finally, you add all the products together. 140 + 21 equals 161, the product of 23 x 7.
While the box method is essentially the same as the standard algorithm, it does a much nicer job of illustrating what’s going on in a multiple-digit multiplication problem. 23 times 7 really just is the sum of 20 times 7 and 3 times 7, based on the basic rules of arithmetic and place value. The box method makes this immediately clear, while the traditional method muddles this simple fact up in a jumble of carrying and odd partial multiplications and sums.
Here’s a numerical breakdown of the “box method” compared with the traditional “longform method”:
Watch the full NPR video explaining the “box method” below:
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