Many students enter Hunter College's developmental mathematics program committing errors (mis)learned years earlier. These errors typically persist into the adult years and it is important to correct them specifically; simply reteaching concepts is not sufficient. Furthermore, there is a strong correlation between completion rate and student perception of the instructor's concern. To address both factors, we developed and tested an instructional technique to see whether giving detailed feedback to students about their errors would facilitate progress through the course. We found that the use of the feedback method had a clear positive effect on women; while for men, complex age by sex interactions and a smaller male sample size made the results less clear.