Web-based instruction provides a new medium for the presentation of instructional activities. In the development of web-based instruction, the designer must realize that the instructional media are merely vehicles for the exchange of ideas. The medium has the capability of addressing individual preferences and styles of learning through its structure and the use of multiple forms of media. Through careful design and adherence to the objectives of instruction and to learners' needs, web-based instruction can provide a successful environment for a variety of learners. In web-based instruction, the design should not be transferred just from one medium to another, but the experience should be redefined with the capabilities of the new medium utilized. Instructional designers must capitalize on the new opportunities that the web provides to learners--to access information from remote locations, to interact with the instruction, to access the instruction at their own pace, to visualize the instruction, and to see the complex relationships in the instruction (Alexander, 1995). Factors in the hypermedia environment, such as visualization, as well as individual student characteristics, such as goal orientation, achievement, and perception, must be taken into account, so the design of web-based instruction enhances the educational opportunities of the learners. ThermoNet was envisioned as a comprehensive supplement for introductory mechanical engineering students. Utilizing many forms of visual media, such as animations, graphics, and video, students would have unlimited access to an interactive web-based environment. This study had four objectives: (1) to determine what students’ characteristics predicted achievement in thermodynamics, (2) to determine what student characteristics predicted the amount of time students spent engaged in ThermoNet, (3) to determine what characteristics impacted students' perceptions of ThermoNet, and (4) to explain the benefits of a web-based instructional environment. The results of this study reveal that web-based instruction may not have a direct impact on students, but the students' goal orientation and preferred mode of learning may impact their achievement. Also, these student characteristics may impact the learner's perception of web-based instruction. More importantly, the results divulge important insights into how web-based instruction can be designed to be a successful learning environment. / text