A critical element of the earth sciences is reconstructing geological structures and systems that have developed over time. A survey of the science education literature shows that there has been little attention given to this concept. In this study, we present a model, based on Montagnero's (1996) model of diachronic thinking, which describes how students reconstruct geological transformations over time. For geology, three schemes of diachronic thinking are relevant: 1. Transformation, which is a principle of change; in geology it is understood through actualistic thinking (the idea that present proceeses can be used to model the past). 2. Temporal organization, which defines the sequential order of a transformation; in geology it is based on the three-dimensional relationship among strata. 3. Interstage linkage, which is the connections between successive stages of a transformation; in geology it is based on both actualism and causal reasoning. Three specialized instruments were designed to determine the factors which influence reconstructive thinking: (a) the GeoTAT which tests diachronic thinking skills, (b) the TST which tests the relationship between spatial thinking and temporal thinking, and (c) the SFT which tests the influence of dimensional factors on temporal awareness. Based on the model constructed in this study we define the critical factors influencing reconstructive thinking: (a) the transformation scheme which influences the other diachronic schemes, (b) knowledge of geological processes, and (c) extracognitive factors. Among the students tested, there was a significant difference between Grade 9-12 students and Grade 7-8 students in their ability to reconstruct geological phenomena using diachronic thinking. This suggests that somewhere between Grades 7 and 8 it is possible to start teaching some of the logical principles used in geology to reconstruct geological structures. ß

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ABSTRACT:There have been few discoveries in geology more important than "deep time"-the understanding that the universe has existed for countless millennia, such that man's existence is confined to the last milliseconds of the metaphorical geological clock. The influence of deep time is felt in a variety of sciences including geology, cosmology, and evolutionary biology. Thus, any student that wants to master these subjects must have a good understanding of geological time. Despite its critical importance, there has been very little attention given to geological time by science education researchers. Of the work that has been done, much of it ignores the cognitive basis for students' understanding of geological time. This work addresses this gap by presenting a validation study for a new instrumentthe GeoTAT (Geological Time Aptitude Test). Consisting of a series of open puzzles, the GeoTAT tested the subjects' ability to reconstruct and represent the transformation in time of a series of geological structures. Montagnero (1992Montagnero ( , 1996 terms this ability "diachronic thinking." This instrument was distributed to a population of 285 junior and senior high school students with no background in geology, as well as 58 high school students majoring in geology. A comparison of the high school (grades 11 -12) geology and non-geology majors indicated that the former group held a significant advantage over the latter in solving problems involving diachronic thinking. This relationship was especially strengthened by the second year of geological study (grade 12), with the key factor in this improvement being exposure to fieldwork. Fieldwork both improved the subjects' ability in understanding the 3-D factors influencing temporal organization, as well as providing them with experience in learning about the types of evidence that are critical in reconstructing a transformational sequence.

A key focus of current science education reforms involves developing inquirybased learning materials. However, without an understanding of how working scientists actually do science, such learning materials cannot be properly developed. Until now, research on scientific reasoning has focused on cognitive studies of individual scientific fields. However, the question remains as to whether scientists in different fields fundamentally rely on different methodologies. Although many philosophers and historians of science do indeed assert that there is no single monolithic scientific method, this has never been tested empirically. We therefore approach this problem by analyzing patterns of language used by scientists in their published work. Our results demonstrate systematic variation in language use between types of science that are thought to differ in their characteristic methodologies. The features of language use that were found correspond closely to a proposed distinction between Experimental Sciences (e.g., chemistry) and Historical Sciences (e.g., paleontology); thus, different underlying rhetorical and conceptual mechanisms likely operate for scientific reasoning and communication in different contexts.

For many decades, science educators have asked, "In what ways should learning the content of traditional subjects serve as the means to more general ends, such as understanding the nature of science or the processes of scientific inquiry?" Acceptance of these ends reduces the role of disciplinary context; the "Footprints Puzzle" and Oregon's "Inquiry Scoring Guide" illustrate this point. In the Footprints Puzzle, students are challenged to distinguish observations from inferences to learn about the nature of science or the culture of science. Oregon's Inquiry Scoring Guide separates content knowledge from inquiry skills. Given long-standing discredit of "the" scientific method, modern views emphasize the diversity of inquiry methods and explanatory ideals across disciplines. Paleontologists, for example, reconstruct the behavior of extinct beasts from fossil footprints using methods of inquiry responsive to this aim. Figuring out dinosaur locomotion depends upon making analogies to the limb structure and behavior of extant species. The history of the Footprints Puzzle demonstrates that an enduring adherence to "a process approach" obscures how conceptualization intertwines with methodology.

Few discoveries in geology are more important than geological time. However, for most people it is impossible to grasp because of its massive scale. In this chapter we offer a solution to this problem based on our research in cognition and education. Our strategy involves the decoupling of geological time between the macro-scale of "deep time which includes the major features of earth history, and whose research we call event-based studies, and the micro-scale of relative time represented by strata, whose research we term logicbased studies. Our event-based study focuses on the problem of learning about macroevolution within the massive time scale of the fossil record. We approached this problem by creating a four-stage learning model in which the students manipulate a series of increasingly complex visual representations of evolution in time. Post program results indicate that students had a better understanding of macroevolution as seen in the fossil record; moreover, they appreciated that different events in absolute time required different scales of time to occur. Our logic-based studies used Montagnero's diachronic thinking model as a basis for describing how students reconstruct geological systems in time. Using this model, we designed three specialized instruments to test a sample of middle and high school students. Our findings indicated that there were significant differences between grade 9-12 and grade 7-8 students in their ability to reconstruct geological systems. Moreover, grade 11-12 geology majors in Israel had a significant advantage over their non-geological counterparts in such reconstruction tasks.

Recently, philosophers of science have argued that the epistemological requirements of different scientific fields lead necessarily to differences in scientific method. In this paper, we examine possible variation in how language is used in peer-reviewed journal articles from various fields to see if features of such variation may help to elucidate and support claims of methodological variation among the sciences. We hypothesize that significant methodological differences will be reflected in related differences in scientists' language style. This paper reports a corpus-based study of peer-reviewed articles from twelve separate journals in six fields of experimental and historical sciences. Machine learning methods were applied to compare the discourse styles of articles in different fields, based on easily-extracted linguistic features of the text. Features included function word frequencies, as used often in computational stylistics, as well as lexical features based on systemic functional linguistics, which affords rich resources for comparative textual analysis. We found that indeed the style of writing in the historical sciences is readily distinguishable from that of the experimental sciences. Furthermore, the most significant linguistic features of these distinctive styles are directly related to the methodological differences posited by philosophers of science between historical and experimental sciences, lending empirical weight to their contentions.

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