Major metropolitan school districts around the United States are implementing computer science in elementary school classrooms as part of the CS for All (CS4All) initiative. Little is known, however, about the success of such a large-scale rollout, especially in terms of equity. In this study we analyze the performance of 4th grade classrooms completing three modules of an introductory computational thinking curriculum, looking at not only overall results but also the variance in performance between high-, mid-, and low-performing schools (as identified by their school report cards). We find that all classrooms are benefiting from the computational thinking (CT) curriculum, making great strides in providing equitable access to CT education. However, statistically-significant differences in performance are present, especially between the high- and low-performing schools, showing that there is still room for improvement in developing strategies and curricula for struggling learners.