Mondays are Club Days at Cornerstone, also referred to as “Marvelous Monday Madness (3M).” After school on Mondays, children can participate in various clubs, such as cooking, biking, running, robotics, band, soccer, etc. Any parent who is cleared as an SBISD volunteer may sponsor a club. Additionally, students may join groups such as the National Junior Honor Society (if qualified) or the Student Council.

In the past, students have also undertaken service projects, such as Locks of Love, the SPCA Pet Drive, and the Stuffed Animal Drive for Local Hospitals.