In the Classroom edited by
View from My Classroom
David L. Byrum Ruamrudee International School Bangkok, Thailand 10510
Teaching Avogadro’s Hypothesis and Helping Students To See the World Differently
Brett Criswell Department of Curriculum and Instruction, Pennsylvania State University, University Park, PA 16802;
[email protected] To prime the reader for what is to come in this article, she or he is requested to consider the following scenario: You walk into a chemistry classroom and there are two balloons tied to separate ring stands—a red balloon labeled “hydrogen” and a yellow balloon labeled “oxygen”. The balloons have been inflated to the exact same size (i.e., have the same volume). With that scenario visualized, the reader is now asked to respond to the following question: Given that the two balloons are in the same room (i.e., are at the same temperature and pressure) and are filled to the same volume with their respective gases, what is true of the number of molecules in the hydrogen balloon compared to the number in the oxygen balloon? While answering the question just posed is likely to be an easy task for the readers of this Journal, it was not an easy task for the students with whom I worked with in my former life as a high-school chemistry teacher. In my current life as a doctoral student in science education, I have come to a deep understanding of why students struggle with questions like this and the concept underlying them. Fortunately, those two lives overlapped for a couple of years and I was able to apply ideas from my graduate education to develop a more effective approach to helping students conceptualize the answer to the above question. During the course of this article, I will describe the ideas that I came across during my graduate coursework and how I used those to more successfully teach not just the concept identified in the title, but also several other concepts within my curriculum. The Concept Behind the Question It must then be admitted that very simple relations also exist between the volumes of gaseous substances and the number of simple or compound molecules that form them. The first hypothesis to present itself in this connection, and apparently even the only admissible one, is the supposition that the number of integral molecules1 in any gases is always the same for equal volumes, or always proportional to the volumes. (1, p 234)
This quote from Avogadro forms the basis for the chemistry principle known as Avogadro’s hypothesis. The reader is likely to recognize that it is this principle that provides the means for correctly answering the question posed above. Upon conceiving this idea, Avogadro recognized other potential applications of it: Setting out from this hypothesis, it is apparent that we have the means of determining very easily the relative masses of the molecules of substances obtainable in the gaseous state, and the relative number of these molecules in compounds; for the ratios of the masses of the molecules are then the same as those of the densities of the different gases at equal temperature and pressure, and the relative number of molecules in a compound is given at once by the ratio of the volumes of the gases that form it.” (1, p 234)
This passage indicates that there are at least two important areas where Avogadro’s hypothesis could have been useful to 19th1372
century chemists:
1. Determining the relative masses of different gaseous substances
2. Determining formulas of “compound” gases (e.g., ammonia) (2).
Unfortunately, almost a half century elapsed before the first area was realized by chemists in the form of a set of atomic mass values determined by Stanislao Cannizzaro via this principle (3). Various explanations have been offered for the delay in applying Avogadro’s hypothesis to such problems.2 One factor that likely contributed to this delay is that the publication of Avogadro’s essay was only a few years removed from Dalton’s proposal of a modern atomic theory and that scientists were still struggling with the notion of the actual existence of atoms. Well-respected scientists throughout the 19th—and even into the 20th—century argued against the validity of the atom as a real entity. The brilliant physicist Ernst Mach said, But let us suppose for a moment that all physical events can be reduced to spatial motions of material particles (molecules). What can we do with that supposition? Thereby we suppose that things which can never be seen or touched and only exist in our imagination and understanding can have the properties and relations only of things which can be touched. We impose on the creations of thought the limitations of the visible and tangible. (4, p 171)
Mach’s words exemplify the empiricist tradition in science: all evidence must be based on those things that can be observed by the senses or by instruments that have been designed to enhance the senses. For empiricists like Mach any idea, such as the atomic theory, “chosen that their subject can never appeal to the senses and therefore can never be tested” produces the result that “the investigator has done more than science, whose aims is facts, requires of him—and this work of supererogation is an evil” (4, p 171). This view of science is in opposition to the realist view adopted by Dalton and Avogadro. The realist position accepts that “There is an existing material world apart from, and independent of, human [sensory] experiences and knowledge” (5). This indicates that unobservable objects proposed by science —such as atoms—can have a real existence no different from observable things—such as test tubes and beakers. The importance of all of this is that it indicates that part of what caused the idea of atoms in general—and Avogadro’s hypothesis in particular—to be only very slowly accepted—and utilized —by the wider scientific community is the ways that different members of that community saw the world. In philosophy, the study of the way people “see the world”, or, more formally, the study of the nature of reality, what things are real and what things are not, and the categories into which those things that exist are placed (6), is called ontology.3 It turns out that understanding this notion of ontology not only helps us understand why the delay between the proposal and application of Avogadro’s
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hypothesis occurred, but, of greater importance to the classroom teacher, why our students struggle in attempting to answer the question that began this article. Ontology and the Molecular Nature of Gases It would be a mistake to think that we should leave it to philosophers to be concerned with ontology. For we all— scientists included—struggle with this notion as we attempt to make sense of the world around us. Think back to the realist and empiricist debate about atoms. At its heart, it was a debate about reality: Are atoms real or are they just an invention of the human mind to solve some scientific problem? It turns out that those who weighed in on the atoms-are-real side of the debate struggled with another issue of reality: What is the relationship between the nature of atoms [molecules] and the nature of gases? Avogadro had a particular response to this question concerning reality and it was this response that made it possible for him to propose his hypothesis ... On the other hand, it is very well conceivable that the molecules of gases being at such a distance that their mutual attraction cannot be exercised, their varying attraction for caloric may be limited to condensing a greater or smaller quantity around them, without the atmosphere formed by this fluid having any greater extent in the one case than the other, and, consequently, without the distance between the molecules varying; or, in other words, without the number of molecules contained in a given volume being different. (1, p 234)
Put in simple terms, Avogadro made a commitment regarding the nature of gases that involved believing that the distance between molecules in a gas was constant and therefore that the size of the molecules did not have an impact on the condensation of caloric (from the caloric theory of heat still prevalent in the early 1800s; ref 7) nor on the number of molecules that would be found in a certain quantity of space. Many other scientists in Avogadro’s day did not make such a commitment regarding the nature of gases, particularly to the relationship between molecular size and caloric, which [partly] explains why they did not accept his ideas.4 Likewise, many of our students today do not make such a commitment regarding the nature of gases particularly to the relationship between molecular size and the number of molecules occupying a certain volume, which explains why they have trouble understanding Avogadro’s hypothesis. Ontology and Misconceptions in Science While it is valuable for science teachers to recognize the existence of certain misconceptions in their students (and there are numerous sources that catalogue these misconceptions; e.g., ref 9), it is much more powerful to understand the basis of these misconceptions. Chi and her co-workers have developed a model to explain the origin of certain misconceptions and the reason that these can be so robust based on the way students “see” the reality of the world around them (9, 10). It is known as the theory of ontological misclassifications. Earlier in the discussion of ontology, the words “... the categories into which those things that exist are placed” were italicized; this was done to prepare the reader for the fact that Chi et al.’s model is based on the notion that one of the central “thinking activities” of humans is to organize entities into “categories of reality”. Further, Chi et al. argue that there are only a few major categories of reality and that two in particular—matter and processes—play a significant role in science learning. The reason for this is that students
often misclassify scientific concepts—such as force, light, and electricity—into the matter category when in fact they belong to the processes category. Tied into this misclassification is a misattribution of properties to these concepts, which makes it difficult for students to understand the appropriate properties, and, therefore, to achieve a proper scientific conception. Let me provide a straightforward example of what Chi and her co-workers were talking about from my own teaching experience. Students in my chemistry class were conducting a set of exploratory activities related to the properties of gases. One of those activities involved holding a partially inflated Mylar balloon over a hot plate for a minute or two then releasing it. The balloon would become fully inflated and then float to the ceiling. In explaining this effect, a student wrote, “The balloon became firm ... it was filled with something ... the heat?” To suggest that heat can fill up an object is to misclassify it as matter and misattribute to it matter-like characteristics. (This is reminiscent of what scientists did with the caloric theory to which Avogadro referred in his one passage quoted earlier.) Understanding Chi et al.’s model has allowed me to recognize the source of such misconceptions and to address them directly to help students reorient their thinking. I have found that such misclassification issues appear in numerous topics such as heat, electricity, and the mole concept and it has changed the way I teach those topics. I have also run across them when covering the topic of gases, which brings me back to the discussion of Avogadro’s hypothesis and how an understanding of students’ views of reality can be used to better teach this idea. Ontology and Avogadro’s Hypothesis From the previous section, the reader might assume that changing misconceptions resulting from misclassifications would be a simple matter of making students aware of their incorrect view of reality (showing them the “error of their ways”) and then explaining to them the proper [scientific] way of looking at things. Over a quarter of a century’s worth of research into conceptual change (11, 12) indicates that it is not quite that simple. Chi et al. offer at least one reason it is more complicated than this: “Further, these ontological commitments are continually reinforced by everyday language, terminology, cartoons, and so forth” (10). Additionally, it is clear that the process category has many more abstract characteristics than the matter category and that these characteristics are not nearly as intuitive to students. At the minimum, between the step of making students aware of their misclassification(s) and the step of explaining to them the appropriate classification, teachers will need to take the time to help students build up the characteristics of what will likely be for them a new category of reality (processes or emergent processes in the most current formulation by Chi et al.). Chi and Slotta provide a concise overview of the instructional strategy necessary to overcome misconceptions of this type: First, familiarize the student in the target ontology, providing some knowledge of the ontological characteristics and engaging the student in reasoning about those characteristics; second, provide instruction that specifically addresses the ontological nature of the concept and (more important) avoids any reinforcement of the inappropriate ontology. (11)
In the next section, I will describe how I have applied the instructional strategy suggested by Chi’s model to the teaching of gases in general and Avogadro’s hypothesis in particular. Be-
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fore that discussion takes place, though, it should be noted that the misclassification underlying student misconceptions in this area is different from the one that Chi et al. have studied. In the case of Avogadro’s hypothesis, the error that students make is to attribute solid characteristics to gases. Both solids and gases belong to the major category of matter and so Chi et al. would not see this as quite as serious a misclassification as the one presented earlier concerning heat. However, it is my experience that this is just as robust a misconception because the matter category of gases is just as abstract to students as is the major category of [emergent] processes. The discussion of the experiences I have had in teaching this subject will support that position. Teaching Avogadro’s Hypothesis Using Chi’s Model As a starting point to utilizing the strategy indicated by their theory, Chi et al. state that, “To apply such an approach in classroom instruction, teachers and curriculum designers must first discern whether a concept is likely to have been ontologically misplaced by the student ...” (10). Following this advice, I begin the section of my introductory course, which focuses on the chemistry of gases, with a set of “exploratory” activities.5 Titled “Walking in the Shoes [Sandals?] of the Ancient Greeks: Exploring Your Views on Matter”, this activity set attempts to elicit students’ initial ideas on properties of matter, particularly those of gases. The first activity in the set involves the students examining a set of three sealed syringes: One containing salt, one containing water with food coloring in it, and the other containing air. They are asked to describe the differences between the matter in the three syringes. Then they are asked to push down on the plunger in each [sealed] syringe, observe what happens and explain any differences. The effect on the syringe containing air and the students’ explanations for that effect will be important fodder for later discussion. This set of “exploratory” activities is followed by a group of lessons or experimental investigations designed to provide a scientific perspective on the properties of gases that can then be compared to the students’ everyday conceptions. The opening lesson in that group is one that develops the opposing views of Democritus and Aristotle regarding the fundamental nature of matter. Central to the philosophical debate between those two views was Democritus’ famous pronouncement that, “Nothing exists except atoms and empty space” (13) and Aristotle’s counter opinion that “Nature abhors a vacuum” (14). As part of this lesson’s discussion, students are asked to vote on whether they believe in the notion of empty space (i.e., support Democritus’ perspective) or whether they oppose this notion (i.e., agree with Aristotle’s views). The typical result is for the majority of students to be unable to accept the fact that there can be empty space in matter and therefore the majority of students side with Aristotle. Previously, it was noted that the explanations students give regarding what happens when they push down on the plunger in the syringe filled with air would be fodder for later discussion. After the vote is taken concerning the Democritus–Aristotle debate and the majority of students weigh in on the no empty space side, I ask someone to describe what happened in the air syringe and to explain the result. While the explanations vary slightly from class to class, they almost always involve some version of a microscopic view of matter that indicates that atoms in a solid are packed tightly together, while atoms in a gas are widely separated. I often ask whether the class as a whole accepts this explanation, and there is rarely a dissenting voice. Then I ask the students to compare their acceptance of that explanation with 1374
their rejection of Democritus’ notion of the void. It is interesting to note that students rarely recognize the incompatibility of the two stances themselves; it is equally interesting how they try to reconcile the two contradictory ideas instead of changing their opinion of one or the other.6 I usually do not go any further at this point than to hold these two ideas up in comparison to each other and to allow students to begin to struggle with their incompatibility. One reason that I initially do not go too deeply into the issue just discussed is that just a couple of classes later, the students conduct an experimental investigation of the pressure–volume relationship using modern computer interfacing equipment to revisit Boyle’s investigation. While the main objectives of this lab are to establish the qualitative [inverse] relationship and introduce students to the mathematics of such relationships, an auxiliary goal is to force the class to revisit the issue of their incompatible viewpoints. Once it has been clearly established that increasing the pressure on a sample of gas causes its volume to decrease, then this question is posed to students: How can a gas be compressed (have its volume decrease) if there is not space between the atoms (i.e., empty space in matter)? This time around, students are forced to confront the issue “head on” because it is noted that Boyle’s law and Boyle’s explanation of this law based on his “corpuscular philosophy” (16) represented one act in a sequence of events that revitalized Democritus’ atomistic views and eventually led to Dalton’s atomic theory. The logical inconsistency of rejecting Democritus’ notion while explaining the compressibility of gases based on greater distances between atoms (than in liquids or solids) is addressed fully. It often turns out that part of the problem in shifting to the proper view of the nature of gases is the students’ hang-up with the term “empty” in the phrase “empty space”. Students seem much more willing (and capable) of making the necessary shift if the discussion at this time includes the modern idea that “empty” may be an inappropriate adjective. The most important aspect to have clearly established with them by the end of this conversation is that there is a far greater distance between the atoms in a gas than those in a solid, a view of reality to which they seem much more willing to commit. Following several other lessons or experiments geared towards exploring the evidence that led to the revival of the atomistic view, an overview of Dalton’s atomic theory is undertaken. While outlining some of the main points of his theory, I guide a discussion of some of the implications of these ideas. Included in this is a consideration of what Dalton’s view of atoms as solid, indivisible spheres indicates about the microscopic nature of solids, liquids, and gases. Students are asked to make drawings representing their perspectives on this and then to describe what those drawings symbolize. That description is compared to a “dynamic” model of the three states of matter made from a partitioned BB board7 or to online computer simulations.8 The main goal of this conversation is to move students towards a view of the nature of gases that includes the notion that the space between gas particles is far, far greater than the size of the particles themselves (or the related idea from the kinetic molecular theory that the total volume of the gas molecules is negligible compared to the volume of the container). Of course, one of the other key ideas from Dalton’s atomic theory is that atoms of different elements will have different masses, which raises the question: How does one measure the mass of atoms? The storyline involved in answering that question takes the class first into an examination of Gay–Lussac’s law
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of combining volumes and then into their confrontation with Avogadro’s hypothesis. The discussion of Gay–Lussac’s law involves a couple of demonstrations to help students visualize this principle, followed by the presentation of a succinct statement of it. This class ends with a question being posed to students: Gay– Lussac’s law simply tells us that gases will react in very simple volume ratio; why would they react in this way? This sets the stage for the culminating lesson—a discussion of Avogadro’s hypothesis. When the students enter the room on the day of this lesson, they are quick to observe that there are two balloons tied to faucets on the front demonstration desk: One that is red and labeled “hydrogen” and one that is yellow and labeled “oxygen” (sound familiar?). As the lesson begins, I quickly review with them Gay–Lussac’s law and then remind them of the question with which they were left the previous day. I ask for any answers, but rarely get anything that has any scientific sophistication to it. “That’s all right”, I tell them because the answer to that question is to be found in the answer to a different question: “Given that the two balloons in front of you are in the same room (i.e., are at the same temperature and pressure) and are filled to the same volume with their respective gases, what is true of the number of [base] particles in the hydrogen balloon versus the number in the oxygen balloon?”9 In addition to posing the question above, I provide the students with what seem to be the only legitimate responses to that question10:
A. There would be more particles in the hydrogen balloon [the common misconception].
B. There would be more particles in the oxygen balloon.
C. There would be the same number of particles in the two balloons [correct answer].
D. There is not enough information provided to correctly answer this question.
Students are given some time to consider the responses and then an initial vote is taken. Assuming that more than one response is produced (which is always the case in this situation), then the class is divided into groups according to the responses given. Each group has a chance to talk among themselves for a few minutes and develop an argument for their choice. At that point, groups must present their arguments (and counter-arguments) to each other (during which time the teacher must act as referee). Once these arguments have been sufficiently explored, the matter is put up to a second vote. Finally, some evidence in support of the correct answer (the normative scientific view) is presented and the ideas are reviewed with students. The key portion of this whole episode is the segment during which students present their arguments. It is important that the teacher refrain from outright criticisms of any of the justifications offered, but that does not mean that she or he cannot occasionally play “devil’s advocate” and interject a challenging question. This may be especially important in the context of this lesson with regard to the ontological issue at stake. For example, in the first year I conducted the lesson in this format, a student defending choice A (above) offered the following argument: “Imagine a small box. You fill it up with golf balls and then you count how many golf balls it took to fill it. Then you dump out the golf balls and replace them with tennis balls and do the same thing. You know that you are going to be able to put more golf balls in the box then tennis balls.” Following this justification, I asked the student to draw a side view of the box with the golf
balls in it and a side view with the tennis balls in it. When he was done, I asked him to tell me what other diagram that he had drawn recently was similar to these two pictures. He immediately recognized that they looked like the drawings of the solid state of matter from the Dalton’s atomic theory lesson . . . so did members of the group who selected choice C. Either through such leading questions as those or arguments presented by students themselves, many of those who at first choose A realize that they did so by applying the wrong attributes (solid-like) to a gas. This often causes many students who initially select A to switch to C when the second vote takes place. To reinforce this as the scientifically accepted answer, I do three things: (i) I offer the third quote from Avogadro presented in this article, (ii) I provide a concise statement of Avogadro’s hypothesis, and [most importantly] (iii) I discuss with students how Avogadro’s hypothesis was able to explain Gay–Lussac’s law (and answer the question posed in the previous lesson). To support this discussion and reinforce the relationship between the two principles, I rely on a set of props built from directions in a Journal article that addresses how to help students visualize Avogadro’s hypothesis (17). I end the lesson by checking that students have the proper view of the nature of gases (and igniting the hydrogen balloon). Conclusion During the second year in which I taught Avogadro’s hypothesis and the precursory topics in the manner outlined in the previous section, I collected data on the impact that this ontologically-oriented approach had. On the test that covered this sequence of topics, 85% of the students responded correctly to the question specifically addressing Avogadro’s hypothesis. On a test nearly a month later, a question representing a slight variation was posed, and 83% of the students answered it correctly. Nearly four months later, a second variation of the Avogadro’s hypothesis question was given on a test, and almost 70% of the students selected the correct choice.11 More interestingly, most of the incorrect answers did not represent the ontological misconception (more particles of the gas made of smaller particles), but a choice indicating that not enough information had been given. I have always been critical of conceptual change research that proved the efficacy of teaching interventions through the results of responses to one—or even a few—multiple-choice questions, so the numbers above only represent a part of the reason that I feel this approach has merit. Just as, or perhaps more, important are examples where students showed their understanding of Avogadro’s hypothesis in more conceptually powerful ways. Such was the case when I performed the electrolysis of water in a Hoffman apparatus12 and a student—observing that there was twice the volume of hydrogen produced as oxygen—said [unsolicited], “So that means there are twice as many hydrogen molecules ...” There are other anecdotal examples of the effectiveness of the approach used, but this one hopefully gets the point across. There is one more point to be made about the numbers presented above that will help me bring this article to a close. Those figures just show the impact that the approach discussed had on student comprehension of a single topic—Avogadro’s hypothesis—and a topic that is probably given minimal attention in most introductory chemistry curricula. If that is really all the discussion in this article was about, then I have, in a sense, “made a mountain out of a molehill”. Hopefully, though, the reader has come to the end of this article with the recognition
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of a greater significance to what was presented herein. For this discussion about how to teach Avogadro’s hypothesis was really just a vehicle for examining the broader pedagogical issue of dealing with a large class of science misconceptions (those based on students’ misplacement of entities into the categories of reality or ontological misclassifications). The savvy teacher can then extract out this broader pedagogical notion and apply it to a whole host of chemistry concepts beyond the arena of Avogadro’s hypothesis. Notes 1. As explained in Scientific Revolutions: Primary Texts in the History of Science (1, p 234), “The words ‘atom’ and ‘molecule’ did not yet have their modern meaning. By ‘integral molecule’ Avogadro meant one molecule of a compound; by ‘constituent molecule’ a molecule of a gaseous element; and by ‘elementary molecule’ (or ‘half molecule’) an atom.” 2. Among those explanations is the suggestion that the “retiring habit” of Avogadro himself made his ideas less widely recognized by other members of the scientific community (2). A second suggestion is that attempts to interpret and apply Avogadro’s hypothesis fell subject to the Duhemian Pitfall and thus led to its inappropriate falsification by other scientists, including Dalton (18). 3. Translated from the Greek, ontology means the study of being. 4. Avogadro indicated that part of the reason Dalton had run into trouble when developing his set of atomic mass values was an incorrect ontological commitment: “Dalton, it is true, has proposed a hypothesis directly opposed to this, namely, that the quantity of caloric is always the same for the molecules of all bodies whatsoever in the gaseous state, and that the greater or lesser attraction for caloric only results in producing a greater or less condensation of this quantity around the molecules, and thus varying the distance between the molecules themselves” (1, p 234). 5. An overview of the set of lessons surrounding this topic and student versions of handouts used in those lessons are found in the online material. 6. Chinn and Brewer (15) have conducted extensive studies of the way that students respond to situations such as this one in which they are presented with anomalous data. They have found that there are many other more likely responses to such situations than for students to change their “theory” regarding this data. This article is one that all science teachers should take some time to read because it challenges the notion of facile conceptual change. 7. Directions for creating the partitioned BB board model can be found in the book ICE Devices: How to Construct Inexpensive Classroom and Lab Tools, sold through the Institute for Chemical Education. The address for the online version of the ICE catalog is http://ice.chem.wisc. edu/catalog.htm (accessed Jun 2008). 8. Some Web pages containing such simulations are http://www. miamisci.org/af/sln/phases/ and http://www.chem.purdue.edu/gchelp/ atoms/states.html (both accessed Jun 2008). 9. Of course the whole controversy whether elemental gases were monatomic or polyatomic was central to the validity of Avogadro’s hypothesis as discussed earlier in the article. Addressing this issue would divert students’ attention from the more fundamental question of how the number of base particles compare and so I have found it easier to ignore this distinction initially and come back to it later. 10. The format being described is based on a lesson structure commonly employed in Japanese science classrooms known as HypothesisExperiment-Instruction (HEI). This lesson structure and some research on its effectiveness have been conducted by Hatano and Inagaki (19). 11. The questions and the class-by-class data are presented at the end of the online material. 1376
12. For those not familiar with either the device or the demonstration being referred to, there is a discussion of the demonstration and a diagram of the device found at http://www.chem.uiuc.edu/clcwebsite/ elec.html (accessed Aug 2008). Additionally, the JCE article “How to Offer the Optimal Demonstration of the Electrolysis of Water” (Zhou, R., 1996, 73, 786–787) could be consulted for a description of how to implement the demonstration.
Literature Cited 1. Baigrie, B. S. Scientific Revolutions: Primary Texts in the History of Science; Pearson-Prentice Hall: Upper Saddle River, NJ, 2004; pp 233–240. 2. Lipeles, E. S. J. Chem. Educ. 1983, 60, 127–128. 3. Chemical Achievers—Stanislao Cannizzaro. http://www. chemheritage.org/classroom/chemach/periodic/cannizzaro.html (accessed Jun 2008). 4. Matthews, M. Planck’s Realism and Mach’s Empiricism. In Science Teaching: The Role of History and Philosophy of Science; Routledge: London, 1994; pp 170–174. 5. Matthews, M. Philosophical Commitments. In Science Teaching: The Role of History and Philosophy of Science; Routledge: London, 1994; pp 37–41. 6. Ontology. http://en.wikipedia.org/wiki/Ontology (accessed Jun 2008). 7. Fowler, M. Teaching Heat: The Rise and Fall of Caloric Theory. http://galileo.phys.virginia.edu/classes/109N/more_stuff/TeachingHeat.htm (accessed Jun 2008). 8. Talsma, V. Children’s Ideas in Science. http://www.cedu.niu.edu/ scied/resources/sciencemisconceptions.htm (accessed Jun 2008). 9. Chi, M. T. H.; Slotta, J.; de Leeuw, N. Learning and Instruction 1994, 4, 27–43. 10. Slotta, J. D.; Chi, M. T. H. Cognition and Instruction 2006, 24, 261–289. 11. Posner, G.; Strike, K.; Hewson, P.; Gertzog, W. Science Education 1982, 66, 211–227. 12. Guzzetti, B. J.; Snyder, T. E.; Glass, G. V.; Gamas, W. S. Reading Research Quarterly 1993, 28, 116–159. 13. A Brief History of the Atom. http://www.cerritos.edu/ladkins/ a106/A%20Brief%20History%20of%20the%20Atom.htm (accessed Jun 2008). 14. History of Thermodynamics. http://en.wikipedia.org/wiki/ Thermodynamics#History (accessed Jun 2008). 15. Chinn, C. A.; Brewer, W. F. J. Res. Sci. Teaching 1998, 35, 623–654. 16. Leicester, H. M. The Historical Background of Chemistry; Dover Publications: New York, 1971; p 114. 17. Bouma, J. J. Chem. Educ. 1986, 63, 586–587. 18. Causey, R. L. J. Chem. Educ. 1971, 48, 365–367. 19. Hatano, G.; Inagaki, K. Sharing Cognition through Collective Comprehension Activity. In Perspectives on Socially Shared Cognition; Resnick, L. B., Levine, J. M., Teasley, S. D., Eds.; American Psychological Association: Washington, DC, 1991; pp 331–348.
Supporting JCE Online Material
http://www.jce.divched.org/Journal/Issues/2008/Oct/abs1372.html Abstract and keywords Full text (PDF) with links to cited URLs and JCE articles Supplement An overview of the set of lessons surrounding this topic and student versions of handouts used in those lessons
Questions and the class-by-class data used to assess the impact of this approach
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