Forty-five children aged four-and-a-half to five-and-a-half years old were given number conservation tasks in three conditions: (1) a count condition in which children were helped to count each set after the transformation; (2) a match condition in which children were helped to connect by a string each animal with its peanut; and (3) the standard…

Traditional methods of teaching addition include algorithms that involve right-to-left procedures. This article describes efficient procedures for left-to-right addition and subtraction involving computation and computational estimation that reflect children's natural behaviors observed during activities with unifix cubes. (MDH)