Word reading disabilities (WRD) represent the most common disability in reading; however, questions remain regarding how to design instruction that results in significant, long-lasting effects on word reading outcomes for individuals who experience considerable difficulties that persist within and beyond primary grades. Two related studies examined effects of variations in targeted sublexical content on word reading efficiency of students in grades 2–4 with WRD. Study 1 addressed effects of instruction and practice targeting complex vs. simple letter units. Study 2 addressed effects of instruction and practice targeting multiple pronunciations of a letter unit vs. standard pronunciations alone. In Study 1, statistically significant differences at posttest on taught ( \(\beta =9.43, t\left(56\right)=2.32, p= 0.02; g=0.17, 95\text{\% CI }[0.01, 0.33])\) and untaught \(\left(\beta =8.44, t\left(56\right)=2.09, p= 0.04; g= 0.15, 95\text{\% CI }[-0.01, 0.31]\right)\) words included in Aligned Word Lists favored the complex letter unit condition. In Study 2, statistically significant differences at posttest on taught words included in Aligned Word Lists favored the standard pronunciations condition \((\beta = -4.15, t\left(60\right)= -2.04, p= 0.045; g= -0.18, 95\text{\% CI }[-0.35, 0.004])\) and group differences in average student performance were non-significant on untaught words \(\left(\beta = -0.22, t\left(60\right)= -0.06, p= 0.96;g= -0.01, 95\text{\% CI }\left[-0.17, 0.17\right]\right).\) Given the modest sample sizes (N = 64) and amount of instruction provided in each study (i.e., 6 lessons), further research is warranted to better understand the impact of variations in targeted sublexical content on word reading outcomes for students with WRD in grades 2–4.
