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 w...