Divide the shower curtain into as many squares as you have children (plus a few extra) using the colored masking tape. Each month have children illustrate on a white piece of construction paper cut to fit the square a picture representing something relating to your "theme." You could also do a "Holiday Quilt" or "Monthly Quilt." I keep mine up all year and change the "theme." If the shower curtain is attached to a bulletin board just pin the student made "quilt squares" to the board.