In order to investigate further the effect of SES on students’ progress, a one-way factor analysis of variance was conducted on the experimental group’s literacy test data. The variance of the difference in students’ achievement on the literacy test was explored based on regression unstandardized residuals for the categories of SES. While the factor analysis of variance was found to be significant (F = 3.130, p = 0.015 df = 4.255), multiple comparisons were made between the categories of SES, with the Post Hoc Scheffe criterion revealing that there was no statistically significant difference between different SES categories, thus leading to the conclusion that differentiated instruction did not favor students from certain social groups.