Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Ronald G. Good


Theoretical sampling was used to select 30 high school biology and college zoology students who examined a simulation involving island biogeography. The literature base for the study was scientific reasoning, problem solving, and prescientific conceptions. The research questions were answered using qualitative and quantitative methods. The first research question was: What number and what type of variables would be used to evaluate biological data? The students used 19 categories of variables, and the most frequently used were size, distance, and food. The second research question was: Will students use the controlling variables strategy in this reasoning task? Only four students displayed this ability while analyzing the data. Students used several strategies to "explain away" evidence that conflicted with their hypotheses. The third research question was: To what extent will students use a theory of evolution to explain biological evidence? This rarely occurred, and possible reasons for the missing application of evolutionary theory were: (a) confusion of ultimate and proximate causation, (b) presence of prescientific conceptions, (c) conflict of a literal interpretation of the Bible with scientific reasoning, (d) lack of familiarity with evolutionary evidence, (e) influence of home environment, and (f) teacher effects. The fourth research question was: After students have generated their own hypotheses to explain the data, what effect will a researcher-introduced theory have on the interpretation of data? Most students did not look at the data again, and the great majority of those who did displayed confirmation bias. The fifth research question was: What will students see as the next step in a scientific investigation of this situation? Student responses were categorized into 13 divisions, the most common of which were performing field work and gathering natural history data. The sixth research question was: Will the number of biology courses students have taken make a difference in how effectively they evaluate biological data? The twelfth graders outperformed all groups on almost every analysis. It is hypothesized that most of this can be explained by the effects of their teacher and of informal education, especially the employment of a family member in a science-related field.