Conceptual knowledge of decimal arithmetic.

In 2 studies (Ns = 55 and 54), the authors examined a basic form of conceptual understanding of rational number arithmetic, the direction of effect of decimal arithmetic operations, at a level of detail useful for informing instruction. Middle school students were presented tasks examining knowledge of the direction of effects (e.g., True or false: 0.77 * 0.63 > 0.77), knowledge of decimal magnitudes, and knowledge of decimal arithmetic...