The major objective of this study was to compare the effects of two modalities of instruction and testing--aural and visual. Other considerations were sex differences in achievement and the exploration of a relationship between sex identity and achievement. The eighth grade boys and girls of average intelligence who participated in this study consisted of 64 poor readers (two or more years below grade level) and 64 good readers (two or more years above grade level). In a comparison of the two treatment modes, for all subjects, no significant differences were found. The same finding applied to girls separately. However, for boys who were poor readers, the auditory training was significantly better than the visual. In addition, all boys combined performed significantly better with auditory instruction. When examining sex differences, it was found that the achievement of boys and girls did not differ with auditory treatment. However, with visual instruction, girls performed better than boys. The study shows that boys and girls do learn more effectively by different learning modalities. (Author/TO)