Much has been written about the value of concrete manipulatives for supporting students' mathematics learning. This is particularly true for the domain of fractions and decimals. Understanding of decimal place-value is seen as critical for students' mathematics learning. To understand decimals, students need first to have a solid understanding of fractions as parts of a whole. Teaching about fractions is likely to begin with familiar fractions such as one-half, one-quarter, one-third, etc. In preparation for understanding decimals, students need to understand the idea that one-tenth is one piece of a whole that has been divided into 10 equal pieces. In this article, the authors describe how a simple teaching aid called a Deciwire may be used to help children understand decimals. (Contains 6 figures.)