The study investigated the selective attentional effects of adjunct study questions inserted before or after the presentation of science flow diagrams. The basic design for the study was a post-test only control group design involving a total of 252 students randomly selected from six secondary schools in Ile-Ife, Oshun State Nigeria. These were randomly assigned to two treatment groups and one control group. Four research instruments were developed and used for this study. One-way analysis of variance in addition to the Scheffe test was performed on the data with the alpha level set at 0.05 level of significance. The result showed that students exposed to science flow diagram with inserted adjunct study questions after the diagram significantly out performed those students exposed to science flow diagram with inserted adjunct study questions before the diagram and those of the control. But, there was no significant difference in the mean achievement scores of students who were exposed to science flow diagram with adjunct study question inserted before the diagram and those of the control. (Contains 3 tables.)