The FILE program (flexible inquiry learning environment) is a research tool, which allows researchers in inquiry learning to design and administer learning tasks in which task domain and task model (i.e. the relations between input and output variables) can be adjusted independently, while other factors (e.g. interface) are held constant. Its monitoring facilities allow for on-line measurement of learning behavior. This paper offers one example of the possibilities FILE has to offer to researchers. Data are presented which illustrate the sensitivity of FILE to age differences in inquiry learning outcome and processes. Instructional applications of FILE are also discussed.