Quality of drawings. In Table 6 we present frequencies of subjects' responses that reflect how the quality of a drawing was crossed with the status of an answer (wrong or correct). The data were restricted to the response categories "wrong answer and drawing absent on the pretest, drawing present on the posttest." Drawings were classified into one of two categories. Category 1 represents drawings that adequately mirrored the structure of a problem. Category 2 includes all drawings in which a problem's structure was displayed incorrectly. Appendix B contains an illustrative drawing of each category. Table 6 indicates that correct and incorrect drawings were equally frequent. Correct answers were generally accompanied by correct drawings and wrong answers by incorrect drawings. When a drawing reflected an interpretational error, the answer often reflected the same error.