The eight articles and two commentaries of this theme issue indicate the main lines of thinking represented at a symposium on the comprehension of graphics in text. The common assumption is that graphics per se do not have a direct effect on learning results but are effective only when processed adequately. (SLD)

External representations have a great impact on what and how students learn. One key manner in which environments can operate upon novices' knowledge is through helping them ground their problem solving in an understanding of the situation embodied by the problem. In this paper, students' difficulties in microeconomics problem solving were…