A new supplement for the microbiology text called Mastering Microbiology was recently released by the publisher. I had heard positive things about the Mastering Biology for BIO 181 (pre-req for micro) and decided to implement Mastering Micro in a like manner. For two semesters prior to utilizing Mastering, the average grade overall at the end of the semesters was 74.64% (n=73).Not a bad average but many students indicated they wanted practice and micro is very conceptual. I was not sure exactly what I wanted to see with my students other than overall increase in performance. I made the activities mandatory for 25 pts/semester. The data for two semesters utilizing Mastering resulted in an average of 74.24% (n=79). While I was hoping something miraculous would be apparent, I am 'seasoned' enough to know I may not actually be able to see any direct effect on grades. For each semester only 2-3 students did not do the activities. Several students indicated they appreciated the practice. I will continue using and adjusting it.