In most evaluations of learning disabled children little effort is made to determine the degree of interaction needed between the child and a task to promote correct or effective responding. Most judgments of a child's learning ability are based on data collected by procedures that do not manipulate or extend on initial test performances. This article describes an evaluation procedure that observes the child's ability to use specific learning strategies. By extending on and manipulating initial responses the procedures help determine the amount of interaction needed to influence a child's performance and identify the kinds of instructional interactions that exercise control over the child's responses. Two examples, a copying task and a reading task, are used to illustrate the procedures. The results are purported to have an impact on various instructional and educational decisions.