Although methods for estimating item difficulty are abundant, little attention has been given to the psychological processes involved when a student responds to a single test item. Mastery of educational objectives is not proven when a student supplies the correct answer to items intended to test these objectives. The student's problem solving method may differ from that intended by the test writer; there is a difference between the student employing the desired process and producing the desired product. The usefulness of the Taxonomy of Educational Objectives as a guide for item writing is questioned. (BJG)