23.5.1.4. 1. Pretests. The study began with a pretest to measure comprehension and knowledge of the science principles. The comprehension test was administered by reading a passage aloud to a student and then asking questions. This testing procedure was used regularly throughout the study. At the time of the pretest, the experimental and control children attained 47% correct. In identifying the theme of the passage, 29.2% of the experimental students were successful compared to 27.2% of the control group. A classification and sorting task was used to assess the children's ability to identify and use the analogy underlying the various topics. The teachers presented the children with pictures and asked them to put the pictures that go together in one pile and the other pictures in another pile. At the pretest, 43% (37% control) of the sorting decisions by the experimental groups were based on physical characteristics of the objects, and only 13% (14% control) were based on thematic characteristics.