You’ve heard the phrase “addition by subtraction,” which often refers in a sports context to teams that improve their performance after losing — or getting rid of — perceived superstars. (Think any team that ever had the good fortune of saying goodbye to Alex Rodriguez.)
Now add to your list of catchphrases “subtraction by addition,” which appears to refer in an education context to a Common Core-based method of teaching subtraction. Kelsey Harris of the Heritage Foundation explains for the Daily Signal.
For third graders learning Common Core math in Georgia, there are four ways to subtract—and only four ways allowed. The picture above is just one of the methods for subtraction under Common Core straight from RedState editor in chief Erick Erickson’s third grade daughter’s math book.
Missing from the four methods: borrowing and carrying numbers. You know, the old-fashioned-taught-the-same-way-for-decades-granny-method-not-approved-by-bureaucrats subtraction.
According to this third grade textbook, students must take about six steps (at minimum, depending how you count) to subtract just two numbers. And if you don’t show your work, circle the right numbers and “count up” correctly, you haven’t proven that you’ve mastered the “why” of the problem.
This latest news should surprise no one who has paid attention to other interesting revelations involving Common Core math.
