students' difficulties in learning and applying scientific concepts are often caused by knowledge that is fragmented and incorrectly interpreted. To remedy such difficulties, the authors propose an explicit instructional method that teaches a coherent procedure for interpreting a scientific concept, and that induces students to use this procedure for explicitly diagnosing and correcting defects in their pre-existing knowledge. To test this method, the concept 'acceleration' was taught to individual students under conditions where they could be observed in detail and tape-recorded during the entire learning process. As a result of such instruction, students revised their highly deficient previous knowledge about acceleration and were able to interpret this concept almost flawlessly across a diverse set of problems.