One issue involved is the degree to which the required response must be authentic. Asking a student to actually measure the length of an object with a ruler is more authentic than presenting the student with a drawing of a ruler and an object to be measured. Systematic observations of students doing mathematics as they work on a project supported by their responses to probing questions are more authentic indicators of their ability to do mathematics than a test score compiled by totaling the number of correct item responses. As noted by the California Mathematics Council and EQUALS (Stenmark, 1989), students' success should be evaluated while working on worthwhile in¬vestigations or tasks. One example is this performance task;