Teaching mathematical concepts is important. In a time when students' performance on basic skills is being emphasized, teachers must be alert not to stress computation at the expense of concepts. Understanding the meaning of a fraction differs from knowing how to add fractions. A lack of conceptual knowledge of a fraction can contribute to incorrect performance in computational skills with fractions. The same can be said about other mathematical concepts, such as percent, decimals, division, factoring, like terms, square root, and so on.