| Although the use of graphic organizers to facilitate comprehension of content area texts has been the subject of numerous investigations, research findings for the effectiveness of graphic organizers are still equivocal. Moreover, a comprehensive research synthesis has not been conducted on the effects of graphic organizers for improving reading comprehension of students with learning disabilities. The purpose of this dissertation was to quantitatively synthesize graphic organizer intervention studies conducted for enhancing reading comprehension and recall of students with learning disabilities by using meta-analytic procedures. Studies eligible for the research synthesis consisted of research sources published from 1971 to 2000. Fourteen studies that used graphic organizers as an intervention for students (K–12 th grade) with learning disabilities were analyzed. Effect sizes (Cohen's d) were calculated by dividing the difference between the treatment and comparison group means by the pooled standard deviation. Additionally, aggregated effect sizes were calculated by instructional feature, graphic organizer feature, length of intervention, instructional group size, instructional materials, dependent variables, measures, and methodological features.; The overall findings of this meta-analysis revealed moderately large effects (weighted mean effect size = .76) of graphic organizers on learning from text materials. In terms of instructional features, the results clearly indicated the following: (a) graphic organizers used before and after reading facilitated initial and subsequent learning of students with learning disabilities in content areas, (b) graphic organizer interventions produced very large effects (weighted mean effect size = 1.39) when used as substitutes for text materials, and (c) the use of experimenter-constructed graphic organizers for student with learning disabilities was effective in enhancing their learning in content areas.; Graphic organizers with the hierarchical and central format with or without pictures resulted in very large effects. All but one graphic organizer interventions focused on expository text. The weighted mean effect size for studies that used materials matched to students' reading ability was larger than that of the studies that used materials matched with their grade level.; Only five studies measured maintenance of performance. Students in graphic organizer conditions outperformed students in comparison conditions on maintenance tests. The weighted mean effect size of graphic organizer instruction on tests of maintenance was .60. However, graphic organizer instruction appeared to have no significant transfer effects. |
