Ellis showed a subtraction problem, performed both using the traditional regrouping, or borrow-and-carry, algorithm and using an example from the common core. Here’s a screenshot of the two methods.

The vertical subtraction algorithm we learned in school doesn’t make this clear — it ... and that’s where compelling students to learn a variety of techniques for subtraction, for example, ...

Many schools have misinterpreted the Common Core by requiring students to solve subtraction problems by memorizing the traditional algorithm, the “counting up” method and the “counting down ...