Meta-analysis of 85 single-subject design studies comparing direct instruction to other teaching strategies found the effects to be substantial for students with learning disabilities; however, when qualified by IQ and reading levels strategy instruction (SI) had better effects for the high IQ group. For the low-IQ discrepancy groups, higher effect sizes were yielded for a Combined DI and SI Model when compared to all competing models. With the exception of handwriting, DI's effects were all above 0.8 (i.e., reading and mathematics).