This study assesses the effectiveness of critical thinking drills (CTDs), a repetitious classroom activity designed to improve methodological and statistical thinking in relation to psychological claims embedded in popular press articles. In each of four separate CTDs, students critically analyzed a brief article reporting a recent psychological study by answering a set of 10 critical thinking questions in relation to it. Student responses were subsequently self-scored through an instructor-led discussion session. Results showed that the average CTD score increased linearly between the first and final assessment. These results suggest that critical thinking in relation to scientific claims found in secondary source material can be successfully taught and quantitatively assessed.