The common core does require some nontraditional teaching methods in math—but using number sentences and having students show their work are not among them.

First of all, not all number sentences are equations. A number sentence is a sentence about numbers, which could be an equation, like 2 + 3 = 5, but also an inequality, like 5 > 3.

Twenty-four first-grade children were asked to write number sentences and select appropriate alternative number sentences for addition and subtraction word problems. Responses were qualitatively ...