To develop problem-solving measures, it is useful to conduct a cognitive task analysis aimed at pinpointing specific changes in the learner's knowledge — including changes in conceptual knowledge and strategic knowledge. The author describes several projects in which researchers measured the problem-solving skill of learners who interacted with computer-based games and simulations involving mathematics, science, or technology. He suggests two forms of assessment: tests of conceptual knowledge, including openended verbal questions involving troubleshooting, redesigning, and explaining; and tests of strategic knowledge, including behavioral assessments of learners' strategies in solving transfer problems. An instructional simulation is a multimedia environment that models the behavior of some system and allows people to interact with it as a way of promoting learning. Learning to program occurs in a computer-based simulation environment that meets the three criteria of interactivity, including nonverbal forms of representation, and requiring that learners engage in problem solving.