The use of computers for educational and instructional purposes has become a more and more important field in Educational Psychology. This work deals with the possibilities of enhancing students‘ motivation and information processing with computer-based learning environments. Central attention is given to the use of hypertextual information in different computer programs. Three different kinds of learning environments have been developed: a Computer-Based Tutorial, a Goal-Based Scenario and a „pure“ Hypertext-environment. All three programs contain the same ecological hypertextual information about the influence and factors of oil and sea and were able to be used on local platforms and through a Web-Browser. Assessing students‘ structural knowledge through a concept-mapping method showed evidence of enhanced knowlege acquisition through the situated learning environment of the Goal-Based Scenario (GBS). An investigation of motivational factors showed significant decrease of learners‘ motivation in the Hypertext and the Tutorial environment, while the GBS supported the maintainance of motivated information processing. Similar results have been found assessing informal reasoning through argumentation. The group participating in the GBS developed a broader, more rational and more balanced reasoning related to a given provocative hypothesis. Tests about the memorizing of single facts showed advantages of the Tutorial.