This study investigated the effects of several elements of instruction (objectives, information, practice, examples and review) when they were combined in a systematic manner. College students enrolled in a computer literacy course used one of six different versions of a computer-based lesson delivered on the web to learn about input, processing, storage and output of a computer. The six versions of the program consisted of (1) a full version that contained information plus objectives, practice with feedback, examples and review, (2) a version without objectives, (3) one without examples, (4) one without practice, (5) one without review and (6) a lean version containing information only. Results indicated participants who used one of the four versions of the computer program that included practice performed significantly better on the posttest and had consistently more positive attitudes than those who did not receive practice. Implications for the development of computer-based instruction are explored.