This study was conducted to determine how the pattern of learning on an abstract concept, plate tectonics, differed between groups of different cognitive levels, sex, and intelligence quotient (IQ). The intensive time-series design was used to examine the achievement of eighth grade and ninth grade earth science students. The unique characteristic of this study was the use of the intensive time-series design to reveal differences in patterns of learning between groups. Results indicated that no definite trend was present as learning occurred among the concrete cognitive tendency students, while a strong positive trend existed as learning occurred in the formal cognitive tendency group. Achievement was greater for students with higher IQs than for those with lower IQs. No clear achievement differences were observed between the sexes. The study indicated the power of the intensive time-series design which permitted researchers to investigate learning as a dynamic process. (DWH)