One major purpose of this investigation was to determine and compare the effects of three different perceptual situations (screening, neutral, and conflict) on kindergarten and first grade children's ability to use the transitive property of the equivalence relation "same length as" and the two order relations "longer than" and "shorter than". A total of 96 subjects (49 kindergarten and 47 first grade children) were chosen from the local public school population. Trained examiners administered the specially developed Knowledge of Terms Test and the Conservation of Length Relations Test (CLRT) individually to the children. On the basis of CLRT scores, subjects were classified as being high, medium, or low in conservation ability. CLRT materials were red, green, and blue sticks, soda straws, and pipe cleaners which the children judged and compared for equivalence in length. Results indicate (1) children in both grade levels and in all three conservation levels were able to use the transitive property in the neutral situation in many more instances than in either the screening or conflict situation and (2) first grade children significantly outperformed the kindergarten children. (WY)