This study was designed to determine whether a student's level of critical thinking would be increased by exposure to programmed materials which emphasized the use of qualifying words in avoiding over-generalizations. Seventy 8th graders were randomly divided into two groups--one experimental, the other control--which were judged to be equivalent on the basis of scores computed from six pretests--Cornell Thinking Test, Iowa Vocabulary and Reading Subtests, SRA Educational Ability Test, a sentence completion test, and a paragraph composition exercise. The control group used materials dealing with interpreting literature and improving skills in English mechanics while the experimental group used materials focusing on the use of qualifying words in verbal settings. Results of the post-test indicated that (1) the experimental group made significant gains in total number of qualifying words used in sentence completion, (2) the control group made significant gains on mean scores on the critical thinking post-test, and (3) no difference was noted between total number of qualifying words used by the two groups in paragraph composition. Further investigation was recommended to determine the effectiveness of the experimental materials if used over longer periods of time and if presented without paper-pencil restrictions. (Author/JM)