Abstract Current high school Earth Science curricula and textbooks organize scientiWccontent into isolated “units” of knowledge. Within this structure, content is taught, but inthe absence of the context of fundamental understandings or the process of how the sciencewas actually done to reach the conclusions. These are two key facets of scientiWc literacy. Ihave developed curriculum from a historical perspective that addresses two particular unitsof study in Earth Science (“geologic time” and “plate tectonics”). The curriculum traces theevolution of the theory of plate tectonics. It includes contextualized experiences for stu-dents such as telling stories, utilizing original historical texts, narratives, and essentialquestions, to name a few. All of the strategies are utilized with the goal of building under-standing around a small set of common themes. Exploring the historical models in this wayallows students to analyze the models, while looking for limitations and misconceptions.This methodology is used to encourage students to develop more scientiWcally accurateunderstandings about the way in which the world and the process of scientiWc discoverywork. Observations of high student engagement during the utilization of this contextualizedapproach has demonstrated that a positive eVect on student understanding is promising.
1 Introduction
Until 2000, the New York State Earth Science curriculum (New York State EducationDepartment 1993, 1970) was organized into “units”, as many Earth Science textbooks arecurrently (see, for example, Hess et al. 2002; Tarbuck and Lutgens 2006). For decades,“Geologic History” and “Plate Tectonics” were two typical content “units” of instruction inboth Earth Science text books and the NYS curriculum. Within these chapters, as well asmost others, “[c]oncepts are considered as absolute truths that were empirically ‘discov-ered’ in a linear and context independent manner” (Justi 2000, p 209). The current NYScore curriculum (New York State Education Department 2000), though rearranged into
G. Dolphin (&)Union-Endicott High School, 1200 East Main Street, Endicott, NY 13760, USAe-mail: [email protected]
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broad, theme-like “standards,” still retains the same sense of the “absolute” nature of ourscientiWc knowledge.
Solomon et al. (1992, 1994) posited the idea that utilizing a historical approach to teach-ing science, rather than traversing the traditional “units”, allowed students to develop theirknowledge of scientiWc concepts in a much more authentic way. Being taught in the contextof the original controversy surrounding competing scientiWc models, students learned whycertain explanations were accepted over others, facilitating their own conceptual change.One of my particular enthusiasms is developing a curriculum which traces the historicaldevelopment of the one physically unifying theory of the Earth: the theory of plate tecton-ics. Plate tectonics is diYcult to understand for students because it involves processes thatare inaccessible to direct observation. The plates move only millimeters per year, convec-tion within the mantle is hidden from view, and radioactive decay, the source of energy forthe process, is a very abstract phenomenon.
Copious scholarly literature supports the idea of teaching science from a historical per-spective (AAAS 1989; Clough 2003; Justi 2000; Matthews 1994; NRC 1996; Wandersee1985). The objectives of this approach are research informed and include enhancing scien-tiWc literacy (AAAS 1989; Nuhfer and Mosbrucker 2007), addressing student misconcep-tions about the nature of science (NOS) (Clough 2003, 2006; Justi 2000; Moreno 2007;Matthews 1994), predicting student misconceptions about content material (Wandersee1985), enhancing conceptual change (Clough 2006; Solomon et al. 1994), modeling scien-tiWc discovery as described by Lawson (2004), and increasing student interest and motiva-tion (Solomon et al. 1992).
After reviewing many sources about the history of aspects of the dynamics of the Earth(see appendix for references), I synthesized a rough time line denoting some of the majordiscoveries or shifts in understanding of the dynamics of Earth. Once completed, Iabstracted the time line along some common themes (Rutherford and Ahlgren 1990), or bigideas (Wiggins and McTighe 2005). The common themes, discussed below, represent threeof Wve (Miller and Duggan-Haas, in review) that are used to organize the entire course.Once the common themes were ascertained, essential questions (Wiggins and McTighe2005) were developed. The purpose of essential questions is to lead students toward uncov-ering the common themes. After this, it was a matter of Wnding, or in most cases, develop-ing contextualized activities and models (Boulter and Buckley 2000; Gilbert and WattIreton 2003; Gobert 2005; Justi 2000) that are both supported by history and utilize strate-gies informed by research. These strategies include telling stories (Ellis 2001; Stinner1995; Wilson 2002), utilizing original historical texts (Matthews 1994), narratives (Metzet al. 2005), dramatizations (Begory and Stinner 2005), and period literature (Cartwright2007), encouraging discussion and reXection (Piaxão et al. 2004), and student constructeddiagrams (Gobert 2000; Gobert and Clement 1999; Johnson and Reynolds 2005). Aninventory of the diVerent modes of representation and the order of model introduction tostudents is included in Fig. 1, which has been modiWed from Boulter and Buckley (2000).The activities are then woven into instruction in a manner similar to that of the “integratedinstructional units” of Singer et al. (2006).
This paper will describe and provide rationale for the organization of a series of contex-tualized activities that traces the evolution of the theory of plate tectonics, an enormouslyimportant scientiWc concept. The ultimate goal of this contextualized approach is not forstudents to be taught scientiWc “truth”, but for them to understand a method of seekingknowledge which can lead to many truths, and to analyze these truths critically whilerespecting diVerences of opinion. In science as in history, however, the devil is in thedetails.
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2 Models
An important part of the contextualized approach is the use, discussion, and critique of mod-els. Models play an important role in teaching science content and teaching about the natureof science. Much can be said concerning the use of models as a pedagogical tool in scienceeducation, (see, for instance, Gilbert and Watt Ireton 2003; Gilbert and Boulter 2000;Halloun 2007), however, this is tangential to the scope of the paper and so will be addressedonly brieXy. Students are told that their personal perception of a particular phenomenon iscalled a mental model (Gilbert et al. 2000) and that learning is a model building process; viz.students building their mental conceptual models of particular target phenomena (Gilbert andWatt Ireton 2003). During instruction, students are often asked to reXect upon their learningby comparing their current mental model with one which they may have held previouslyconcerning the same concept. Students also mimic scientiWc process by testing theirexpressed models—mental models which are put into the public domain (Gilbert et al. 2000).
One major challenge was taking concepts which represent some of the major discoveriesor paradigm shifts that occurred during the evolution of the theory of plate tectonics anddeveloping diVerent modes of representation (Boulter and Buckley 2000) for them (Fig. 1).Because students often confuse a simpliWed model for its target (Boulter and Buckley2000), they need to be exposed to many diVerent modes of representation in order to facili-tate enrichment of their mental models and their understanding of the concept (Gilbert andWatt Ireton 2003; Stevens and Collins 1980). The Chart in Fig. 1 is a tool for taking inven-tory of the modes of representation of a concept, in this case, mountain building, andsequencing their introduction in a pedagogically sensible way, viz. from concrete toabstract (Boulter and Buckley 2000).
Fig. 1 Modes of representation of mountain building (After Boulter and Buckley 2000). Key to classiWcationscheme for Fig. 1 (Boulter and Buckley 2000). Modes of Representation: Concrete, three dimensional modeleither scale or functional; Visual, diagram, animation, or video presentation; Gestural, kinesthetic represen-tation, relying on the movement of the body; Verbal, representation that is read or heard, i.e. simile, metaphor,analogy; Mathematical, equations or formulas, some computer simulations. Attributes of Representation:Qualitative, involving distinctions, or comparison based on qualities; Quantitative, involving distinctions orcomparison based on precision or numerical information; Static, no change in model through time; Dynamic,model changes in relation to time; Deterministic, predictable change through time; Stochastic, changes arevariable with time and based on probability
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By organizing the models historically and allowing students to discuss and debate thembased on “goodness of Wt” (Gilbert and Watt Ireton 2003, p 17), the process of how sciencereally works is itself modeled. Research on this practice indicates that it enhances students’scientiWc literacy (Justi 2000).
My motivation is for students to sharpen their own critical thinking skills by separatingthemselves from their own mental models and analyzing those models for strengths andlimitations (Gilbert and Watt Ireton 2003). Critical assessment of models by students isencouraged with the use of model analysis worksheets used throughout the entire course ofstudy.
3 Common Themes and Essential Questions
A key aspect of this contextualized approach is its foundation in common themes. Ruther-ford and Ahlgren (1990) espouse the importance of common themes because “(t)hey areideas that transcend disciplinary boundaries and prove fruitful in explanation…” Wigginsand McTighe (2005, pp. 66–67) describe big ideas as being “essential for understanding”.They are “at the core of the subject” and “are arrived at, sometimes surprisingly slowly, viateacher-led inquiries and reXective work by students”. The contextualized approach beingpresented focuses on a few common themes within the study of the evolution of plate tec-tonics. These common themes come from Miller and Duggan-Haas (in review): To under-stand (deep) time and the scale of space, models and maps are necessary; evolution anduniformity deWne the Earth system; and the Xow of energy drives the cycling of matter. Ifocus on these themes, as they underpin the concepts that are necessary for scientiWc under-standings that the Earth is very old, the processes causing change at the Earth’s surfacehave remained in operation throughout its history, and plate tectonics is the mechanismresponsible for cooling the Earth’s interior. A fourth theme that is emphasized is the tenta-tiveness of scientiWc explanations. There have been many, many alternative hypothesesconcerning the age of the earth, (geologists vs. physicists), the origin of various rockformations (neptunists vs. plutonists or catastrophists vs. uniformitarians), and the cause ofdeformation of the earth (uplift, shrinking, drifting or sinking), not to mention variousexplanations for continental contact (land bridges or continental drift). Scientists tend tofall into a “camp” based on the way they interpret data and upon a priori beliefs that theybring to the investigation. When new observations are made, enhanced by new technolo-gies, or when new ways of interpreting old data are used, scientiWc explanations are oftensubject to change to accommodate those observations and alternative interpretations.
The inquiry process begins with asking essential questions. These are “questions that arenot answerable with Wnality in a brief sentence,” but are used “to stimulate thought, to pro-voke inquiry, and to spark more questions” (Wiggins and McTighe 2005, p. 106). Wigginsand McTighe (2005, p. 106) consider essential questions to be “signposts to big ideas”. Inthat vein, essential questions are used to “uncover” the major understandings describedabove. The unit begins with and revolves around the essential question, “If weathering anderosion have been leveling the land for at least the last 4 billion years, why are there stillmountains on Earth?” Students brainstorm various processes that could be responsible forthe appearance of mountains on Earth and identify evidence for those processes. Typicalresponses are given in Table 1. The activity is used as both an “engage” activity (Bybeeet al. 2006) to “hook” students into the inquiry process and as a diagnostic assessment ofthe students’ level of knowledge regarding Earth dynamics. It is interesting to note thatmany students see erosional agents, viz. rivers and glaciers, to be the cause of mountains. In
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other words, they see mountains as being what’s left after the processes of erosion havedone their work; the places in between valleys. The idea of plate tectonics does come up fordiscussion, however since their last exposure to that particular concept was two to threeyears prior, their use of the vocabulary shows no real grasp of the underlying concepts. Thisis born out with such student comments as, “Earthquakes cause the plate tectonics to smashinto each other, creating mountains.”
The students are then led through the historical process of discovery, guided by a seriesof other essential questions. How do we know that the crust of Earth has changed? Howlong has this change been taking place? What causes the change? A brief outline document-ing the structure of the curriculum, with rationale now follows.
3.1 Essential Question One: How do we Know That the Crust of Earth has Changed?
Students are Wrst exposed, through the strategy of story telling, to Danish born anatomist,Niels Stensen (Nicolas Steno) (1638–1686), whose careful observations facilitated a bigbreakthrough in the understanding of the history and processes on Earth (after Cutler2003). While dissecting the head of a great white shark, Steno noticed that the teeth werealmost identical to rock formations, called “tongue stones” at the time, which were found inthe mountains of Italy, but were of unknown origin. He hypothesized that these rock forma-tions were really sharks’ teeth preserved in rock. From that he surmised that the rock sur-rounding the teeth must be marine in origin, and that there have been major changes atEarth’s surface that are not accounted for in the Bible. The purpose of discussing Steno isto relate to students the importance of his three ideas which continue to be the underpinningprinciples of modern stratigraphy; super position, original horizontality and lateral continu-ity. By applying these principles to observations made from various geologic cross-sec-tions, the idea of change through time becomes obvious.
Another fundamental principle of modern geology emerged in the 18th century, and isintroduced to students through the historical narrative, “A Very Deep Question: How Old isthe Earth?” by Clough et al. (2006). In this narrative, James Hutton (1726–1797), a Scot-tish born gentleman farmer realizes that wasting of his land occurred only in very smallincrements. His medical background gave him both Newton’s mechanistic way of lookingat the processes taking place on earth, and a feeling for the cyclicity (the life cycle, circula-tion) of the wasting and rejuvenation of the land (Clough et al. 2006). Hutton put forth acornerstone of modern geology by explaining changes that had taken place in the past byusing processes at work in the present. He states,
Table 1 Student responses to the essential question “If weathering and erosion have been leveling the landfor at least the last 4 billion years, why are there still mountains on Earth?”
ProcessesMovement of plates, volcanic eruptions, metamorphism, faulting/folding, earthquakes, doming, plate
tectonics, glacial erosion, erosion of canyons by rivers, some rocks less resistant to weathering, verticalforces from within Earth, mountains just really big to start with.
Evidence
We see land forming at volcanoes, we see the faults and feel the motion of the earth in an earth quake, we seemetamorphosed rocks, we see folded/faulted mountains, we see marine fossils and sediments well abovesea level, we see intrusive rocks at the surface, we can measure continental movement, we can see foldedor domed mountains, we see volcanic mountain chains such as the Hawaiian Islands. We see modernerosion at glaciers and rivers.
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“In examining things present, we have data from which to reason with regard to whathas been; and from what has actually been, we have data for concluding with regard tothat which will happen thereafter. Therefore, upon the supposition that the operationsof nature are equable and steady, we Wnd, in natural appearances, means for concludinga certain portion of time to have necessarily elapsed, in the production of those eventsof which we see eVects” (emphasis mine) (Hutton 1788, in Sengör 2001, pp. 18).
With this narrative, students have the example of how Hutton’s past experiences inXu-enced the way he explained his observations. Students interpret examples of geologiccross-sections using Steno’s three principles, and Hutton’s principle, later called uniformi-tarianism, by describing the sequence of events that led to the eventual structure of thecross-section. I have found this activity to be a good formative assessment of studentunderstanding of these principles.
Story telling continues as the class learns about William Smith (1769–1836), who chartedthe world’s Wrst geologic map of his native England. He was able to do this by correlatingindex fossils across England and most of Scottland. The students are drawn into the storywhen they learn that Smith’s wife was mentally ill, and that he actually ended up in debtor’sprison until his map was Wnally published and he had made enough money to buy his wayout (Winchester 2001). Stinner (1995) and Wilson (2002) suggest that adding “human inter-est” encourages students to tie their emotions to the facts and facilitate the internalization ofthe information. Student understanding of this concept is evaluated when they imitateSmith’s techniques of correlation via an activity where they utilize the entire room to con-struct a three-dimensional sedimentary sequence based on the correlation of index fossils(Fig. 2a, b). Through these examples students can observe that there has been a change inboth the structure of the rocks and the life represented by the fossils found in the rocks.
3.2 Essential Question Two: How Long has This Change Been Taking Place?
In the narrative by Clough et al. (2006), students also read how the understanding of theendless cycles of mountain building, erosion, and deposition led Hutton to the conclusionthat the Earth has “no vestige of a past and no prospect of an end” (Hutton 1797, in Savoyet al. 2006). This Xew in the face of Bishop Ussher’s 6,000-year Biblical chronology,
Fig. 2 Two variations in scale for modeling correlation in the fashion of William Smith. Students run stringconnecting layers of similar age based on index fossil data
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which was very popular at that time. The class then discusses issues of emerging ideas thatdo not correspond to the currently accepted model. This issue is seemingly as prevalenttoday with the swaying of public opinion in terms of global warming, which enters the dis-cussion as a modern example, as it was 200 years ago.
The students are then asked, “How can we estimate the age of the Earth?” Students cannow utilize Hutton’s uniformitarian idea of the slow but steady accumulation of landderived sediment in the ocean to postulate that the depth of ocean sediments divided by anestimated sedimentation rate could approximate the age of the Earth. I also relate to stu-dents some of the methods described at length by Jackson (2006). Georges-Louis Leclerc,Comte de BuVon (1707–1788) used the cooling rates of various sized iron spheres to pro-ject how long it would take for a sphere the size of the Earth to cool. His estimate was 86,667 years. William Thomson (1824–1907), later known as Lord Kelvin, engaged in a three-pronged approach for gaining the age of the earth, utilizing the newly developed laws ofthermodynamics to estimate the age of the sun, estimating cooling of the earth based ongeothermal gradient measurements, and calculating the eVect of tidal friction on the rota-tion of the Earth. Kelvin’s estimate of up to 20,000,000 years, though quite a bit longerthan Comte de BuVon, was still not enough to satisfy geologists like Charles Lyell (1797–1895) and biologists like Charles Darwin (1809–1882). They believed the Earth to be farolder, of an age suYcient to accommodate not only the changes observed on the Earth’ssurface, but also the theory of evolution. Stinner and Teichmann’s (2003) “Lord Kelvin andthe age of the Earth Debate: A Dramatization” is a wonderful complement to this argu-ment. While reading this debate, students can get exposure to how diVerent scientists for-mulate explanations, and they discuss the diVerence between the deductive, equation basedreasoning of the physicists and the inductive, observations based reasoning of the geolo-gists and biologists.
The discovery of radioactivity in late 19th century is then described. Human interest isagain added by relating some of the tragic stories of the radium watch dial painters of theearly 1920’s (Mullner 1999). After a brief lesson in radioactive chemistry, the students per-form a radioactive decay simulation activity and calculate the half-life of diVerent modelradioactive materials. The implications of this new knowledge are discussed in class in thesequence that follows. First, radioactivity becomes the heat source keeping the earth’s inte-rior warm, disqualifying the thermodynamic arguments of BuVon and Thomson. Second,this new understanding allows scientists to actually date the rocks on Earth. ConWrmationof an ancient Earth came from Bertram Boltwood (1870–1927) when, in 1905, he came upwith Wgures of 400 to 2,500 million years for the age of rocks that he dated using this newtechnology (Jackson 2006). We explore student concepts of geologic history by building a4.6 billion year timeline from one long piece of lamp shade fringe with tassels strung acrossthe classroom ceiling. There are 460 tassels, each representing 10 million years. Studentshang cards representing major events in Earth’s history in places along the time line wherethey think each happened in time. Student misconceptions about the antiquity of the Earthare revealed when they see that even something so distant in their eyes as the existence ofthe dinosaurs took place a relatively short time ago. Students want to locate dinosaur exis-tence between 100 and 200 tassels ago, where, according to the model, it is just over six outof 460 tassels ago.
3.3 Essential Question Three: What Caused the Change?
Students are shown and asked to evaluate an early model developed by Aristotle (384–322BCE), as described in Sengör (2003). The model is used to explain the reason for the
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existence of continents and ocean basins, how they interchanged over time, the existence ofmaritime and continental climates, and the location of both seismic and volcanic activity(Fig. 3a–c). This was such a strong model that it lasted fairly well intact up through the19th century (Sengör 2003). See also Jules Verne’s, 1871, “A Journey to the Center of theEarth” (Verne 1992) in which Verne makes reference to the “galleries” that lead to theEarth’s interior. When asked whether they feel the model does a good job of explainingobservations, most students agree that it does. I then utilize the “wet sponge” model(Fig. 3d) as an analogue to the Aristotle model, for clariWcation. Water is poured onto oneside of a dried, Xattened sponge, and immediately begins to expand on that side. Studentsdiagram the demonstration and discuss the strengths and limitations of this model. Johnsonand Reynolds (2005) found that concept sketches were very eVective in engaging studentsin active participation, facilitating student personalization of understanding, and being atool to evaluate student understanding. Students then try to determine whether it makessense that the earth behaves like a sponge—expanding when water is added. I show themwhat happens when water is added to a beaker of dry gravel (another model for the earth).They diagram the second demonstration and compare it to the Wrst. When there seems to betoo much wrong with Aristotle’s model, they move to another possibility—the 18th centurymodel of thermal contraction. I demonstrate to the class, quite convincingly, the strength ofthis model by placing a wet paper towel over an inXated balloon (Fig. 4a) and creatingmountains as the balloon is slowly deXated (Fig. 4b).
Students diagram the pattern of mountains produced from the thermal contraction modeland then sketch the pattern of mountain ranges on earth with the use of globes and worldmaps. Thermal contraction becomes yet another discarded theory when students realizethat not only do mountains on the model show up in a completely diVerent pattern (roughlyhexagonal) when comparing them to the pattern of mountain ranges on a world map (longand narrow), but there is also a lack of symmetry about Earth’s mountain ranges that is nei-ther observed nor expected from this contraction model of deformation. Students combinethose observations with the fact that the Earth would have had to have been impossibly bigin order to accommodate the measured displacements of the crust in such mountain rangesas the Alps (Oreskes 1999), and again the model becomes clearly inaccurate. Students arethen reminded of Hutton with regard to his ideas of vertical igneous forces (Clough et al.2006) as yet another possible mode of mountain formation. Students predict what thatdeformation should look like with a diagram and see that dome mountains Wt their predic-tion based on this model, but they observe that the structure of the major ranges does notreXect this kind of deformation.
The idea that mountains were caused by vertical forces (gravity or igneous pressures)was superseded eventually by other scientists, most notably Alfred Wegener (1889–1930),who proposed his theory of continental drift in 1912. Students are presented with a mapshowing the sequential break up of Pangaea alongside a map supporting its contemporaryalternative hypothesis, land bridges (Fig. 5). In two groups, they make predictions whichmay be supported by either of the models and engage them in a debate pitting the “drifters”against the “Wxists,” similar to that outlined in Piaxão et al. (2004). Students reenactWegener’s thought process by constructing their own Pangaea during an activity that asksthem to cut out continents and glue them together, matching up mountain ranges and loca-tions with similar fossils and geology.
A concept that is important for students to understand is how often science has beenresponsible for valuable new technology. New technology, in turn, enables scientists tomake new or better observations which may lead to new discoveries and to the reWnementof their earlier understandings. It is also interesting to note that much of the money used to
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fund technological development in the US comes from taxes supporting the militaryservices and the defense industry. It is explained how magnetometers were Wrst used toscan ocean waters in the 1940’s and 50’s to Wnd mines and enemy submarines. In theprocess, scientists discovered a strange pattern of magnetic anomalies on the Xoor of theocean. Students parallel this discovery by utilizing a small model representing a section ofseaXoor that has embedded and reversed magnetic signals. The reversals are observed bydragging a small compass over the model and then mapping the “zebra stripes” in thissection of seaXoor.
Another example of defense funded technology is the creation of the World WideSeismic Network (WWSN), which was used to “listen” for nuclear bomb testing during the
Fig. 3 Cross-sectional model of a portion of earth describing global tectonics as presented by Aristotle in hisMeteorologica (351 BCE), and interpreted by Sengör (2003). (a) shows a schematic view of subterraneanchannels which can be from small capillaries to large galleries in size. (b) shows where channels are full ofXuids (mostly water) the ground is swollen into uplands and where the channels are not full the crust isdepressed into basins. These areas are stable and seismically quiescent. Water leaves the right side via evapo-ration or Xow through the channels to the left. (c) shows the result of the shifting of Xuids to the left. Areasbetween upland and basin are unstable and therefore show higher incidence of seismic and volcanic activity.(d) is an example of the “wet Sponge” analogue to the model. It works by adding water to the left end of a dryand Xattened sponge. Students watch the “continent” rise as in the Fig. 3c. Figure 3a–c used with permission
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years after the nuclear test ban treaty. This is one more way, albeit indirect, that the discov-ery of radioactivity inXuenced our understanding of Earth dynamics. It provided scientistswith seismic information of a precision that had not even been dreamed about earlier. Nowseismologists could examine the location of an earthquake in three dimensions. They coulddetermine which way the ground moved along the fault, giving them a “window” into thestructure of the Earth’s interior. Students participate in activities paralleling some of thesediscoveries, such as epicenter triangulation, analyzing waveform data to infer the structureof the Earth’s interior, and observing patterns in epicenter and hypocenter locations.
This early seismic information, when combined with other seaXoor data collected andcompiled by marine geologist Harry Hess (1906–1969), set the stage for a paradigm shiftthat would fundamentally change the way that scientists understand the dynamics of theEarth. To model this, students use maps showing various sea Xoor data indicating sea Xoorage, heat Xow, sediment thickness, topography, volcanic activity, and seismicity (afterSawyer et al. 2005). Students are asked to draw a spatial/static diagram of two diVerentportions of sea Xoor, one centered on the mid-Atlantic ridge and one on the Peru–Chiletrench, to integrate the data they observe on their maps. Students then add a causal/dynamicaspect and develop explanations for the patterns they observe. With a little direction, theydevelop an explanation similar to Hess’ theory of sea-Xoor spreading. Gobert (2000) andGobert and Clement (1999) hold that this sort of sequential diagramming promotes modelbuilding and inference making in students. The importance of such female geologists asMarie Tharp (b. 1920) and her mapping of sea Xoor topography and discovery of the oce-anic “ridge-system” is also discussed with students here.
Finally, following the lead of Fred Vine (b. 1939) and Drummond Matthews (1931–1997),the class diagrams the observations made to date; combining the zebra stripe magneticanomalies with Hess’ theory of seaXoor spreading and Wegener’s idea continental drift.They cut out and reenact J. Tuzo Wilson’s (1908–1993) elegant model (Fig. 6a, b) of thetransform fault (Earle 2004). Their diagrams now have all of the information which ledscientists to the development of the theory of plate pectonics. This is the Wrst mention of“plate tectonics” since the beginning of instruction more than four weeks earlier. Wefurther strengthen the theory by doing a Hawaiian “hot spot” geology activity (NationalScience Teachers Association 1996) where a small Xask of dyed, heated water is place inan aquarium of water. Students witness the “plume” of heated water which strikes thebottom of a styrofoam, Xoating “crust”, creating volcanic island chains (Fig. 7). We alsodiscuss Tanya Atwater’s (b. 1943) contributions from her study of the San Andrea’s fault
Fig. 4 This “thermal contraction” model has the balloon being the Earth and the wet paper towel as the crust.Slowly letting air out of the balloon represents the contraction of the cooling earth. Mountains are built as thepaper towel wrinkles
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(Atwater 2001). Due to its high seismic activity, a comprehensive understanding of thisarea is very relevant to the students.
The class discusses the mechanics of subduction zones and we develop models such asthe “wet towel” analogy of slab pull subduction (Stern 1998) and the “slinky” model of ten-sion and extension (Fig. 7b). The “slinky” model explains very nicely the observation of
Fig. 5 Two competing theories explaining continental contact. Top is the “land bridge” theory of JamesDana. Bottom is the theory of continental drift of Al Wegener
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tensional earthquakes in the shallower subduction zone and compressional earthquakes inthe deeper subduction zone. To describe the driving force behind the change at the surface,students are reminded about the internal heat engine powered by the decay of radioactiveelements. They are told that this is just another case of energy Xowing from a region of highconcentration to one of low. Plate tectonics is the eVect on matter of this Xow of energy.Students Wnally see maps showing actual measurements of continental movements taken bysatellite (Jet Propulsion Laboratory 2004). In this way, the process of scientiWc discoveryhas been shown to students as being the “truth” of science; that science is something we
Fig. 6 Students recreate J. Tuzo Wilson’s elegant paper model of a transform fault (from Earle 2004)
Fig. 7 Models used to strengthen the theory of plate tectonics. (a) shows a hot red water “plume” causing avolcanic island chain along the Styrofoam crust. (b) shows a slinky modeling the subducting crust to supportthe idea of “slab pull” subduction. The spring shows extension through the upper part of the mantle and com-pression where it collides into the stiVer mantle
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“do” rather than something we “believe in”. Above all, the Xuid, ever changing nature ofscientiWc knowledge is shown to supersede the absolute nature of scientiWc “truth”.
The culminating activity, also used as a summative assessment of student learning, is areiteration of the original question: “If weathering and erosion have been leveling the landfor at least the last 4 billion years, why are there still mountains on Earth?” Students reXecton their original list generated about a month prior and then create a new list in the sameformat, listing processes and evidence. The students are then given a sheet of paper con-taining a diagrammatic transect of the Earth’s surface. The transect starts on the left show-ing the east coast of China, going west across the PaciWc Ocean, through South America,and on to the west coast of Africa. The students are instructed to create a spatial/static dia-gram by drawing in the evidence from their list that supports the theory of plate tectonics.This includes all of the sea Xoor data studied and including mineralogy, along with seismicand volcanic information. They are then asked to add arrows to this diagram to show thecausal/dynamic aspects of the model. These include the processes involved in plate tecton-ics (i.e. convergence, divergence, convection, etc.). By creating this diagram, students wereable to articulate the relationships between the evidence for plate tectonics and the pro-cesses. The diagrams also demonstrated their understanding of the Xow of energy as themechanism of plate tectonics. Examples of student work can be seen in Fig. 8a–c.
4 Conclusion
This curriculum design based on the historical approach to teaching plate tectonics hasbeen evolving for approximately 4 years. The use of overarching essential questions to“uncover” a few common themes is geared to help students understand the content. Addingto that, the teaching of content which utilizes historically contextualized activities hasobservably raised the interest level of the students. Through the entire month of instruction,students entered class asking if they were going to “get the answer” today, and left classasking, “When are we going to Wnd out why there are still mountains?” As early models arepresented to the students, each is met with great optimism for being the “right answer”. Aseach is discarded because it doesn’t Wt observations well enough, the students become morecircumspect and critical of its replacement. Student skepticism has been obvious as theyask “Why should we believe that this one is the truth?” or “What is going to be wrong withthis one?” The students showed a great relief in Wnally uncovering the “answer”, and havefurther commented that plate tectonics not only “makes sense” to them but is just plain“obvious” as an explanation. They have been present for and have participated in theprocess of science. The analysis of models for strengths and limitations is a valuableopportunity in itself for promoting critical thinking in students, whose future will assuredlybe challenged by issues such as global warming, water pollution, urban sprawl, growingpopulations, sustainable economies, etc. It is my hope for my students that similar thoughtprocesses will enable them to make better decisions, whether they are in the voting booth orin the county board meeting (or possibly in the White House). The approach presented hereis proof that such contextualized experiences for high school students are both plausibleand valuable for increasing scientiWc literacy.
Fig. 8 (a–c) Sample of work demonstrating student knowledge of theory of plate tectonics. Students draw aspatial/static diagram with evidence to support plate tectonics then add a causal/dynamic aspects by drawingin the processes involved in plate tectonics
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1 C
G. Dolphin
1 C
Evolution of the Theory of the Earth
Finally, there are many resources both popular and scholarly for the history of scienceand in this case the history of plate tectonics (See Appendix for a bibliography of resourcesused in developing the curriculum). However, from my research, there are few contextuali-zed experiences which have been created for incorporation within the science classroom,and far fewer within Earth Science. To read and assimilate the information available andthen create interesting mechanisms to transfer the information to students, i.e. narratives,dramatizations, activities, and models is a huge eVort. “Teachers and researchers oftendescribe a gap between research and practice” (Abell and Lederman 2007, p. xiii). The his-tory and philosophy of science scholars are encouraged to help bridge that gap by creatingand publishing these types of contextualized experiences for the classroom teacher. Wewould all beneWt greatly.
Acknowledgements I would sincerely like to thank Michael Clough and HsingChi vonBergmann forencouraging me to put my work on paper. I would also like to thank Rebecca Remis and Charles Turecek fortheir eVorts in making the manuscript much more readable.
References
Abell S, Lederman N (eds) (2007) The handbook of research on science education. Lawrence Erlbaum Asso-ciates Publishers, NJ, p 1330
American Association for the Advancement of Science (AAAS) (1989) Benchmarks for scientiWc literacy:project 2061. AAAS, Washington, DC, p 418
Atwater T (2001) When the plate tectonic revolution met North America. In: Naomi Oreskes (ed) Plate tec-tonics: an insider’s history of the modern theory of the earth. Westview Press, pp 243–263
Begoray D, Stinner A (2005) Representing science through historical drama: Lord Kelvin and the age of theearth debate. Sci & Edu 14(5):457–471
Boulter C, Buckley B (2000) Constructing a typology of models for science education. In: Gilbert J, Boulter C(eds) Developing models in science education. Kluwer Academic Publishing, pp 3–17
Bybee RW, Taylor JA, Gardner A, Van Scotter P, Carlson Powell J, Westbrook A, Landes N (2006) BSCS5E instructional model: origins, eVectiveness and applications. Colorado Springs, CO: BSCS. http://www.bscs.org/pdf/bscs5efullreport2006.pdf
Cartwright J (2007) Science and literature: towards a conceptual framework. Sci & Edu 16(2):115–139Clough M (2003) The nature of science: understanding how the “Game” of science is played, Chap. 8. In:
Weld J (ed) The game of science education. Allyn and Bacon, pp 198–227Clough M (2006) Learners’ responses to the demands of conceptual change: considerations for eVective
nature of science instruction. Sci & Edu 15(5):463–494Clough M, Olson J, Stanley M, Colbert J, Cervato C (2006) Iowa State University, Ames, IA, USA. Project title:
humanizing science to improve post-secondary science education: pursuing the second tier. NationalScience Foundation Course Curriculum and Laboratory Improvement (CCLI) Phase II (Expansion) Pro-gram. Please contact the principal investigator, Michael Clough, at [email protected]
Cutler A (2003) A seashell of the mountaintop: a story of science, sainthood, and the humble genius whodiscovered a new history of the earth. Dutton Publishing, 298 pp
Earle S (2004) A simple paper model of a transform fault at a spreading-ridge. J Geosci Edu 52(4):391–392Ellis B (2001) The cottonwood: how i learned the importance of storytelling in science education. Science
and Children, NSTA publication, January 2001, pp 43–46Gilbert J, Boulter C (eds) (2000) Developing models in science education. Kluwer Academic Publishing, 387 ppGilbert J, Boulter C, Elmer R (2000) Positioning models in science education and in design and technology
education. In: Gilbert J, Boulter C (eds) Developing models in science education. Kluwer AcademicPublishing, pp 3–17
Gilbert S, Watt Ireton S (2003) Understanding models in earth and space science. National Science TeachersAssociation Press, 124 pp
Gobert J (2000) A typology of causal models for plate tectonics: inferential power and barriers to understand-ing. Int J Sci Edu 22(9):937–977
Gobert J (2005) The eVects of diVerent learning tasks on model-building in plate tectonics: diagrammingversus explaining
Gobert J, Clement J (1999) EVects of student-generated diagrams versus student-generated summaries onconceptual understanding of causal and dynamic knowledge in plate tectonics. J Res Sci Teach36(1):39–53
Halloun I (2007) Mediated models in science education. Sci & Edu 16:653–697Hess F, Kunze G, Leslie S, Letro S, Millage C, Sharp L, Snow T, National Geographic Society (2002) Earth
science: geology, the environment, and the universe. Glencoe/McGraw-Hill, Columbus Ohio, 970 ppHutton J (1797) Excerpts from the theory of the earth. In: Savoy L, Moores E, Moores J (eds) (2006) Bedrock:
writers on the wonders of geology. Trinity University Press, pp 56–59Jackson P (2006) The chronologers’ quest: the search for the age of the earth. Cambridge University Press,
291 ppJet Propulsion Laboratory (2004) GPS time series: global velocities. http://sideshow.jpl.nasa.gov/mbh/
series.htmlJusti R (2000) Teaching with historical models, Chapter 11. In: Gilbert J, Boulter C (eds) Developing models
in science education. Kluwer Academic Publishing, pp 209–226Johnson J, Reynolds S (2005) Concept sketches – using student- and instructor-generated, annotated sketches
for learning, teaching, and assessment in geology courses. J Geosci Edu 53(4):85–95Lawson A (2004) T. rex, the crater of doom, and the nature of scientiWc discovery. Sci & Edu 13(3):155–177Matthews M (1994) Science teaching: the role of history and philosophy of science, Routledge, 287 ppMetz D, Klassen S, McMillan B, Clough M, Olson J (2005) Building a foundation for the use of historical
narratives, paper presented at the 8th international history, philosophy, sociology and science teachingconference, July, 2005, University of Leeds, Leeds, UK, 21 pp
Miller S, Duggan-Haas D (In review) DeWning big ideas in earth scienceMoreno N (2007) Teaching science in the 21st century – Teaching the nature of science: Wve crucial themes,
national science teachers association WebNews Digest, http://www.nsta.org/main/news/stories/nsta_story.php?news_story_ID = 53152
Mullner R (1999) Deadly glow: the radium dial worker tragedy. American Public Health Association, 192 ppNational Research Council (1996) National Science Education Standards (NSES), National Academies Press,
http://books.napedu/readingroom/books/nses/html/ See especially content standard GNational Science Teachers Association (1996) Volcanoes and hot spots. Project Earth Science, National Science
Teachers Association, pp 119–125New York State Education Department (1970) Regents earth science syllabus. The University of the State of
New YorkNew York State Education Department (1993) Earth science program modiWcations. The University of the
State of New YorkNew York State Education Department (2000) Physical Setting/Earth Science Core Curriculum. The Univer-
sity of the State of New York, 15 ppNuhfer E, Mosbrucker P (2007) Developing science literacy using interactive engagements for conceptual
understanding of change through time. J Geosci Edu 55(1):36–50Oreskes N (1999) The rejection of continental drift: theory and method in American Earth Science. Oxford
University Press, 420 ppPiaxão I, Calado S, Ferreira S, Alves V, Morais A (2004) Continental drift: a discussion strategy for second-
ary school. Sci & Edu 13:201–221Rutherford F, Ahlgren A (1990) Science for all Americans. Oxford University Press, 246 ppSawyer D, Henning A, Shipp S, Dunbar R (2005) A data rich exercise for discovering plate boundary
processes. J Geosci Edu 53(1):65–74Sengör A (2001) Is the present the key to the past or the past the key to the present? James Hutton and Adam
Smith versus Abraham Gottlob Werner and Karl Marx in Interpreting History. Geological Society ofAmerica Special Paper number 355:51 pp
Sengör A (2003) The large-wavelength deformations of the lithosphere: materials for a history of the evolu-tion of thought from the earliest times to plate tectonics. Geol Soc Am, Memoir 196:347pp
Singer S, Hilton M, Schweingruber H (2006) America’s lab report: investigations in high school science, vol5. National Academies Press, pp 82–85
Solomon J, Duveen J, Scot L, McCarthy S (1992) Teaching about the nature of science through history: actionresearch in the classroom. J Res Sci Teach 29:409–421
Solomon J, Duveen J, Scot L (1994) Pupils’ images of scientiWc epistemology. Int J Sci Edu 16:361–373Stern R (1998) A subduction primer for instructors of introductory-geology courses and authors of introduc-
tory-geology textbooks. J Geosci Edu 46(3):221–228Stevens A, Collins A (1980) Multiple conceptual models of a complex system. In: Snow R, Federico P,
Montague W (eds) Aptitude, learning and instruction volume 2: cognitive process analyses of learningand problem solving. Lawrence Erlbaum Associates, Hillsdale, NJ, pp 177–197
Stinner A (1995) Contextual settings, science stories, and large context problems: toward a more humanisticscience education. Sci Edu 25(5):555–581
Stinner A, Teichmann J (2003) Lord Kelvin and the age of the earth debate: a dramatization. Sci & Edu12:213–228
Tarbuck E, Lutgens F (2006) Earth Science: New York Student Edition, Pearson Education, Inc., UpperSaddle River, NJ, 804 pp
Verne J (1992) A journey to the center of the earth. Originally published in 1864 in France as Voyage auCentre de la Terre Readers Digest, Pleasantville, NY, 280 pp
Wandersee J (1985) Can the history of science help science educators anticipate students’ misconceptions?J Res Sci Teach 23(7):581–597
Wiggins G, McTighe J (2005) Understanding by design 2nd edn, Association for Supervision and CurriculumDevelopment, 372 pp
Wilson E (2002) The power of story, American Educator, American Federation of teachers publication,pp 8–11
Winchester S (2001) The map that changed the world: William Smith and the birth of modern geology,Harper Collins, 329 pp
Appendix: Some of the resources used to produce the unit on the historical development of the theory of plate tectonics
Bolles E (1999) Galileo’s commandment: 2,500 years of great science writing. W. H. Freeman, 485 ppCutler A (2003) A seashell on the mountaintop: a story of science, Sainthood, and the Humble Genius who
discovered a new history of the earth. Dutton Publishing, 298 ppDanson E (2006) Weighing the world: the quest to measure the earth. Oxford University Press, 289 ppGrant J (2006) Discarded science: ideas that seemed good at the time, facts. Figures and fun, 336 ppHellemans A, Bunch B (1988) The time tables of science: a chronology of the most important people and
events in the history of science. Simon and Schuster, 660 ppJackson P (2006) The chronologers’ quest: the search for the age of the earth. Cambridge University Press, 291 ppMullner R (1999) Deadly glow: the radium dial worker tragedy. American Public Health Association, 192 ppOreskes N (1999) The rejection of continental drift: theory and method in American earth science. Oxford
University Press, 420 ppOreskes N (2001) Plate tectonics: an insider’s history of the modern theory of the earth. Westview Press, 424 ppRepcheck J (2003) The man who found time: James Hutton and the discovery of the earth’s antiquity. Perseus
Publishing, 247ppSavoy L, Moores E, Moores J (eds) (2006) Bedrock: writers on the wonders of geology. Trinity University
Press, pp 56–59Sengör AMC (2001) Is the present the key to the past or the past the key to the present? James Hutton and
Adam Smith versus Abraham Gottlob Werner and Karl Marx in Interpreting History, Geological Soci-ety of America Special Paper number 355, 51 pp
Sengör AMC (2003) The large-wavelength deformations of the lithosphere: materials for a history of the evolutionof thought from the earliest times to plate tectonics, the geological society of America, Memoir 196, 347 pp
Verne J (1992) A journey to the center of the earth, originally published in 1864 in France as Voyage au Cen-tre de la Terre, Readers Digest, Pleasantville, NY, 280 pp
Winchester S (2001) The map that changed the world: William Smith and the birth of modern geology, Harp-er Collins, 329 pp
Author Biography
Glenn Dolphin is an Earth Science Teacher at Union-Endicott High School, Science Teachers Associationof New York State (STANYS) Director at Large for Earth Science, a member of the New York State teamfor the Revolution in Earth Science Education, and a Digital Library for Earth System Education (DLESE)Ambassador to New York State. He holds a B.S. in geology from Binghamton University, a M.A. in Geol-ogy from The Johns Hopkins University and a M.A.T. from Binghamton University. He is currentlyenrolled as a Ph.D. student in the Science Education department at Syracuse University. A recipient of theNational Association of Geoscience Teachers (NAGT) “Outstanding Earth Science Teacher Award,” hispedagogical interests focus on the development and use of models in teaching Earth Science, and on incor-porating the history and nature of science within instruction. He has presented many workshops for teachersand has reviewed and edited several science textbooks.
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