A learner is a cognitive system that develops by students information and knowledge-processing activities. To maximize the learners cognitive development, knowledge-intensive environments are essential particularly for achieving environmental knowledge. This paper proposes a model based on decision analysis approach in such a way could evaluate students cognitive development toward environmental problem A learner is a cognitive system that develops by his own information and knowledge-processing activities. To maximize the learner ' s cognitive development, knowledge-intensive environments are essential to help him explore a situation, construct his own concepts, and discover general laws by his own problem- solving activity (1). The lecturer, as knowledge facilitator, has an extremely complex problem on his hands. Before deciding exactly what course of action to take, he needs to consider many issues, including suitable environments and the uncertainties involving students abilities and school resources. Decision analysis provides effective methods for organizing a complex problem into a structure that can be analyzed (2). In particular, elements of a decision structure include the possible courses of action, the possible outcomes that could result, the likelihood of those outcomes, and eventual consequences to be derived from the different outcomes. Figure 1 shows a flowchart for the decision analysis process. For illustration, assume a lecturer needs to make a decision on which tutoring method to apply for motivating a class of under-achievers in engineering mechanics. A few alternatives may be considered: drill and practice, peer tutoring, hands-on activity, and on-line tutoring. Thereafter, variables associated with the alternatives are identified. The variables may be uncertainties such as students interest, their abilities, and availability of computer resources. Utility functions are assessed in order to model the way the lecturer values different outcomes and trade-off competing objectives. Decision analysis tools such as influence diagrams (2, 3) and decision trees (4, 5) are then used to model the problem for determining a preferred alternative. For complex models, computer software such as DPL (6) is available to auto-mate the computation. Additional analysis such as sensitivity study (7) may be performed to answerwhat if' questions such as: a computer resource is available, does it imply that on- line tutoring leads to a better student motivation?. If the answer is positive, then the lecturer may want to consider obtaining more information on that variable prior to making the decision.