A weakness of many interactive visual programming languages (VPLs) is their static representations. Lack of an adequate static representation places a heavy cognitive burden on a VPL s programmers, because they must remember potentially long dynamic sequences of screen displays in order to understand a previously written program. However, although this problem is widely acknowledged, research on how to design better static representations for interactive VPLs is still in its infancy. Building upon the cognitive dimensions developed for programming languages by cognitive psychologists Green and others, we have developed a set of concrete benchmarks for VPL designers to use when designing new static representations. These benchmarks provide design-time information that can be used to improve a VPL s static representation.

considered simply, but a more complex evaluation of the effects of performing the tasks. For example, an educational activity that learners complete quickly and accurately is of no value if they learn nothing from it. We have adapted the programming walkthrough technique to help design computer-supported educational activities in elementary school science. We present examples from a case study which illustrate ways in which design of an educational activity is similar to and different from design of a user interface. We have found that the walkthrough approach is useful in this new setting, and that it sheds new light on the general task-centered orientation to design. Despite these differences in design problems, we hypothesized that the core logic of task-centered user interface design, and of the associated walkthrough methods, could be adapted to the design of educational activities. We present the results of our exploration of this possibility by describing a case study in which...