Fully online courses and degree programs are popular with students. These courses should provide the rigor and value of traditional learning in a face-to-face classroom to ensure mastery of concepts and learning objectives. This research expands previous work to investigate the effectiveness of online laboratory exercises in enhancing student understanding of core concepts taught in fully online introductory astronomy, physics, and biology courses. Identical classes, with or without an online laboratory, were compared to determine gains in content mastery. A Likert-style survey was also used to quantify student perception of the laboratory component for those courses and measure overall student satisfaction. Results indicated astronomy and physics students in online laboratory courses showed significant gains in mastery of learning outcomes, thereby demonstrating effectiveness; biology students in online courses showed more mixed results. Further, surveys indicated student perceptions strongly support the belief that the labs helped to learn the course material and labs were an effective "hands-on" experience, directly contributing to student satisfaction in all disciplines studied. As such, this study represents an assessment of the effectiveness of different online course designs in achieving student mastery and satisfaction. [Note: The page range (322-356) shown on the PDF is incorrect. The correct page range is 322-355.]