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DOI: 10.1039/C2RP00002D (Paper) Chem. Educ. Res. Pract., 2012, 13, 17-29

Reducing the degrees of freedom in chemistry classroom conversations

Brett A. Criswell
Middle-Secondary Education & Instructional Technology, Georgia State University, 30 Pryor Street, Atlanta, Georgia 30303, USA. E-mail: bcriswell@gsu.edu

Received 16th October 2011 , Accepted 25th November 2011

First published on 8th December 2011

Abstract

Five high-school chemistry teachers were asked to enact a lesson in which they posed a problem for which students were likely to generate solutions based on reasoning that was not aligned with accepted principles of chemistry. Four teachers selected a problem related to the stoichiometry of a reaction; the fifth chose a problem associated with periodic trends. The goal of the research was to understand the kinds of strategies used by these teachers to support students' progress towards more sophisticated conceptualizations of the phenomena being explored. Transcripts of teacher interviews and the discourse contained within the videotapes of the lessons were analyzed to identify similarities and differences in the strategies teachers employed. The data suggest that all of the teachers operated off a common lesson schema that caused them to implement certain pedagogical practices—especially certain discourse moves. This ‘traditional cognitive conflict’ schema from which the teachers' discursive practices seemed to be derived reduced the opportunities for them to gain full access into their students' thinking related to the principles underlying the problems posed. Moreover, it eliminated possible pathways the teachers could have laid down between the conceptions of students and those of chemists. For researchers this study suggests the need to further explore the prevalence of such practices and what prompts their utilization; for teachers this study shows the influence their choice of certain discourse moves can have on a lesson's conceptual trajectory.

Introduction

The emergence of the constructivist (Rosenfeld and Rosenfeld, 2006; Staver, 1998; Windschitl, 2002) and sociocultural (Kelly and Chen, 1999; Lemke, 2001; Scott, 1998) perspectives in science education in the past thirty years has shifted the view of effective science pedagogy from teachers transmitting canonical scientific knowledge to students to teachers facilitating scientific meaning making by students (Kindergarten through Eighth Grade Committee on Science Learning, 2007; Mortimer and Scott, 2003). While there may be disagreement on certain philosophical issues related to these two theoretical perspectives (Bereiter, 1994a; Loughlin, 1992), there is concurrence between these stances in the conviction that students' experience with and appropriation of the discursive practices associated with scientific thinking (i.e. talking and writing science) are central to their learning of science content (Bleicher et al., 2003; Brown et al., 2005; Prain and Hand, 1996). This conviction has been reified in various reform documents as illustrated by the following passage from the United States's National Science Education Standards (NRC, 1995):

The language and practices evident in the classroom are an important element of doing inquiries. Students need opportunities to present their abilities and understanding and to use the knowledge and language of science to communicate scientific explanations and ideas. (p. 144)

Building off the notion that the discursive practices required by students to engage in scientific meaning making must be developed through exposure to the appropriate tools and experiences, key components of effective science pedagogy would thus be (1) helping students develop expertise with the requisite tools and (2) designing experiences which make the relevant practices readily accessible to students. There has been significant research over the last couple of decades as to how science teachers might structure those components in a manner which will be most conducive to promoting science literacy (e.g.Hsu and Roth, 2009; Olitsky, 2007; Tabak and Baumgartner, 2004). Critical features identified in this research tied specifically to the nature of science talk are that teachers must carefully interweave different communicative approaches (Scott et al., 2006), skillfully incorporate multiple forms of questioning (Chin, 2007), and meaningfully integrate everyday and scientific language (Brown and Spang, 2008). These features should be managed in a way that creates congruence between students' ways of knowing and those of canonical science (Lee and Fradd, 1998), a goal that can be achieved by creating ‘hybrid spaces’ in which those ways of knowing can interact (Barton and Tan, 2009).

While research such as that reviewed above has certainly helped to paint a more detailed picture of the characteristics of and possibilities for science classroom discourse, there are also constant reminders of the work that remains to be done. For instance, Scott et al. (2007) recognize one hurdle that has not been completely cleared:

Put briefly, science education researchers are currently in the position where we can point with confidence to the likely conceptual starting points and challenges for students in any area of science learning, but we have rather less to say about how to shape instruction in order to help students come to terms with the scientific point of view. (p. 51)

Translated into the parlance of a Vygotskian (1986) perspective, these authors are suggesting that researchers have not adequately mapped out the terrain between students' everyday concepts and science's formal concepts. Likewise, teachers continue to struggle with how to lay down the proper “language trails” (Scott, 1998, p. 56) which can serve as pathways for students across that unfamiliar terrain. In this paper, data will be presented from lessons enacted by five high-school chemistry teachers who were asked to pose a problem for which their students were likely to generate solutions based on reasoning that was not aligned with accepted principles of chemistry. Specifically, the data selected will focus on how the teachers responded to students' ideas which were different from those of chemists. It will show the ways in which the pedagogical strategies of these teachers—particularly the discourse moves they utilized—may have limited the available pathways along which they could guide students towards more elaborate understandings of the chemical principles related to the problems posed.

Conceptual change and science discourse

In his review of the literature on conceptual change in science education, Duit (2003) suggests that, “In a general sense, conceptual change denotes learning pathways from students' pre-instructional conceptions to the science concepts to be learned” (p. 673). Much as with the researchers Duit cites in his review, what pathways a teacher sees as being available between students' ideas and science's ideas depends on what relationship the teacher perceives as existing between those ideas. It is likewise expected that a teacher's choice of what language trails to lay down will be a function of her/his perception of this relationship. Therefore, a survey of the conceptual change approaches described by researchers and the association between student and scientific concepts as envisioned by those approaches should outline the possibilities for the discourse strategies employed by teachers as they facilitate students' meaning-making efforts.

Hewson and Hewson (1983) suggested four broad categories of conceptual change strategies that were distinguished by their view of students' prior knowledge (pp. 732–733): integration, conceptual bridging, differentiation, and exchange, with the first two assuming that students' prior knowledge could serve as a foundation for building new knowledge and the second two assuming that that prior knowledge would serve as an impediment. Guzzetti et al. (1993) conducted a meta-analysis of the science education literature related to experimental studies of various pedagogical techniques and noted that, “From evidence accumulated in the cluster analysis, we conclude that three instructional approaches affected conceptual change” (p. 145). The three approaches they identified were the learning cycle (pp. 145–146; e.g.Karplus and Thier, 1967), bridging analogies (pp. 146–147; e.g.Clement, 1993), and conceptual conflict (pp. 147–148; e.g.Posner et al., 1982). The first two of these techniques are generally driven by attempts to reconcile students' concepts with those of science when the two are not aligned, while the third focuses on directly confronting students' concepts in such cases.

Although different in several ways, the strategies overviewed above have some common ground: All are based on purely cognitivist views of the conceptual change process in which differences between ideas held by students and those held by scientists are remediated by appeal to the logic and rationality of scientific thinking. In a sense, Duit's (2003) review picks up where Guzzetti et al.'s meta-analysis left off: by noting the limitations of strictly cognitivist approaches (in particular, the ‘classical’ conceptual change model, pp. 674–675), including an emphasis on epistemological considerations over ontological ones and a lack of concern for the affective domain (as addressed in Pintrich et al., 1993). Duit then proceeds to describe the more recent work of scholars who have addressed these shortcomings, such as Chi et al. (1994), who developed an ontology-based model of conceptual change; Sinatra and Pintrich (2003), who took into account motivational factors in their framework; and Dykstra (1992), who recognized the significance of group interactions in the conceptual change process.

While all of the approaches discussed in Duit's (2003) review implicitly or explicitly accept the role that talk and nonverbal forms of communication play in mediating the mechanisms of conceptual change, none foreground the role of discursive interactions to the extent that Klaasen and Lijnse (1996) do. Examining a single piece of transcript from a physics lesson through multiple lenses on conceptual change, they reach the conclusion that the factor that ultimately kept a female student (Jane) from making headway in her understanding of a principle associated with force was not epistemology, ontology, or intentionality—it was a misunderstanding of language between her and the teacher. Interestingly, in a more recent piece co-authored with Beeth and Thorley, Hewson (1998) addresses classroom discourse as the first element in a set of guidelines for teaching for conceptual change (pp. 203–204).

Increasing acknowledgment of the critical part that discourse plays in supporting science learning in general and promoting conceptual change in particular has lead to efforts to provide teachers with frameworks for orchestrating science talk. One such framework is the accountable talk model of Michaels et al. (2008); while not expressly developed for science classrooms, the principles of accountability to the learning community, knowledge, and reasoning on which this model is built can easily be utilized in those settings. Windschitl et al.'s (2008)heuristic for progressive disciplinary discourse was specifically constructed for use by science teachers, and implementation of its six design principles could facilitate conversations that would help students attain more sophisticated understandings of science phenomena. With what such frameworks suggest about the interplay between conceptual change and science discourse, a key question becomes, What talk practices are teachers actually using in their classrooms?

Data and research question

The author has become interested in the conceptual change strategies favored by grades 9–12 (U.S. high school) science teachers and how those preferred strategies might impinge on their discourse practices. To that end, the author has been collecting various forms of data (teacher and student interviews, videotapes of lessons, and, most recently, survey responses) over the last several years to be able to paint as detailed a picture as possible as to what approaches are most prevalent and what relationships may exist between those approaches and patterns of interactions in science classrooms. The data presented below was taken from the corpus amassed during the first two years of that larger project when the author was working with ten teachers who had different disciplinary foci: 5 chemistry, 3 physics, and 2 biology.1 Owing to the nature of this journal's readership, the data obtained from the chemistry teachers was chosen for this paper; additionally, although data was gathered from each of these teachers over two years, only samples from that portion obtained in the first year will be presented as it indicates each teacher's natural proclivities towards utilizing talk to facilitate conceptual change.

The five teachers who participated in the study being overviewed (Hannah, Marty, Nancy, Sandy and Sarah—pseudonyms) became involved because the author had had previous contact with them (e.g. the author had met Nancy at a professional development experience and Marty taught in the school from which the author had graduated). Relying on such individuals was necessary because of the challenge of gaining access to schools and obtaining permission to videotape lessons; thus, this represents a convenience sample (Marshall and Rossman, 2006) of the teacher participants. ‘Biographical’ information about each teacher is presented in Table 1.

Table 1 Basic teacher participant ‘biographical’ information
Name Gender Years Teaching Courses Observed General School Information
Hannah F 3 Chemistry I [a heterogeneously-grouped introductory chemistry course] Serves a residential area in eastern Pennsylvania; typical graduating classes range between 160 and 180 students; very limited ethnic diversity (less than 1% of student population is non-Caucasian)
Marty M 8 Honors Chemistry [students are more homogeneously grouped by (high) ability] Located in north central Pennsylvania; a small school district, with graduating classes of ∼160 students; less than 1% non-Caucasian students in the school
Nancy F 12 Regular and Accelerated Chemistry [students grouped by lower (Reg) and higher (Acc) academic ability] Serves a rural area in central Pennsylvania; small school with graduating classes of ∼70 students; less than 1% non-Caucasian students in the school
Sandy F 15 Chemistry I [same as above] Same school as Hannah
Sarah F 2 Academic Chemistry [students are more homogeneously grouped by (high) ability] Located near a metropolitan area in south central Pennsylvania; averages ∼285 students per grade level; ∼10% non-Caucasian student population

There are several aspects of the contexts in which data collection occurred that are likely to have limited the range of the talk practices observed, and these need to be acknowledged: None of the schools were in urban settings, there was a narrow range of socioeconomic backgrounds represented, and the majority of the students were Caucasian. The last aspect is particularly significant because studies have shown that students from Euro-American homes are more likely than students from other backgrounds to engage in talk with family members which can lay a foundation for appropriating the traditional discourse of science classrooms (e.g.Moje et al., 2001). Still there is value in identifying the interactional patterns in the settings available to the author in order to make comparisons to those patterns found in a wider scope of settings.

As noted above, the teachers were asked to pose a problem for which students were likely to propose solutions based on reasoning that was not aligned with accepted principles of chemistry. The four female teachers (Hannah, Nancy, Sandy and Sarah) all employed a problem related to stoichiometry which had been suggested by the author: Given 6.54 grams of zinc, how much sulfur should be combined with it to produce the ideal mixture for a reaction used in model rocket engines? Marty chose a different problem based on past challenges he had faced in teaching periodic trends to his students: Given a set of element cards from a family and a set of element cards from a period (excluding transition metals), what would the order of the elements in the family and in the period be for the atomic radius?2 Each of the participating teachers enacted their problem-focused lesson in introductory chemistry classes that were composed mainly of 11th-grade students. Revisiting Table 1 it can be seen that Hannah's, Nancy's and Sandy's classes were populated by students with a range of academic abilities, while Sarah's and Marty's classes were composed of students who were largely high-achieving in science.

While there were four sources of information gathered for the larger project (lesson videotapes, lesson artifacts, teacher interviews, and student interviews), only two of those provided data germane to this study: lesson videotapes and teacher interviews. The videotapes captured the entire enactment of the lesson in each of the classes in which the participating teachers conducted it. For all five teachers, the ‘entire enactment’ spanned two 42–50 min class periods; Marty and Nancy conducted the lesson in two classes, Hannah and Sandy in three classes and Sarah in four; this resulted in 14 lesson videotapes. Each videotape was transcribed and analyzed according to methods that will be discussed in the next section. With regards to the interviews, each teacher was involved in two pre-lesson interviews and one to three post-lesson interviews (depending on time available for each interview). These interviews were semi-structured and generally focused on the teachers' intentions for the lessons and their perspectives on how the lessons actually unfolded. The interviews were also transcribed and analyzed through procedures described below. These two data sources supported the author in answering the research question, ‘What were the features of the structure of the discourse which emerged as teachers initiated the movement between students' preliminary ideas and the formalized scientific explanation related to conceptual problems posed in five chemistry classrooms?’

Methods of data analysis

During the transcription and a first reading of the interviews, analytical memos (Merriam, 2009, p. 136) were made. After all of the interviews for the teachers had been transcribed and had been subjected to a first reading, the analytical memos were used to generate descriptive codes (Saldaña, 2009). For example, one significant code which emerged was ‘Views of conducting science talk’.

The analysis of the video transcripts went through several stages. The goal of the initial stage was to segment the lessons according to the different actions being performed by the participants. To that end, each transcript was partitioned into task segments (which involved the completion of lesson sub-goals) and step segments (which comprised task segments and which represented the separate actions required to achieve those sub-goals) based on the work of Wells (1999). A key outcome of this first stage of analysis was the recognition that all fourteen lessons videotaped had six task segments in common: (1) Building Up/Posing the Problem; (2) Generating Solutions; (3) Sharing Out Solutions; (4) Conducting Tests; (5) Analyzing the Test Results; and (6) Formalizing the [‘Correct’] Solution. The discourse data examined in this paper will come mainly from the Sharing Out Solutions segments since that is where students' ideas were first examined publicly.

In the second stage, the dialogue within the smaller step segments was broken up into three levels of discourse units based on a hierarchical system developed by Wells (1999). The lowest level—or smallest unit—is the move, which is categorized based on what role it plays in the interaction: initiation (I), response (R), or follow-up (F) (p. 337). Moves are identified at the level of a speaker's turn, with each turn being coded as I, R, or F—although a single turn can be given more than one move code. A combination of two or more moves involving two or more speaker turns constitutes the intermediate level—an exchange. While coding for the type of exchange was useful in the larger project, including these codes will not add any analytical power to the current study and so they will be omitted in the data presented herein. Finally, the highest level—or largest unit—in Wells's system is the sequence which represents a series of exchanges linked together by the focus on a single topic and the maintenance of a certain configuration of speakers.3 In the transcript document for each video, sequences were delineated and numbered, then each turn within the sequence was identified as I, R, or F (or sometimes as a combination of two of these) to show the kind of move(s) it embodied.

The third and final stage of the discourse analysis involved coding each move according to its function. Since the discourse functions in which the researcher was most interested were those related to discussion/debate around the students' proposals, Bereiter's (1994b) notion of science as progressive discourse was utilized to develop these function codes. It was Bereiter's contention that the goal of science was not the search for objective truth, but was to engage in the practice of progressive discourse (p. 4). As he explained this practice, “Sometimes people with opposing views can engage in discourse that leads to a new understanding that everyone involved agrees is superior to their previous understanding” (p. 6). Bereiter viewed progressive discourse not only as the ideal of effective scientific inquiry, but as the ideal of meaningful science classroom talk. In order to achieve that ideal, he argued, it was necessary for four commitments to be upheld: (1) A commitment to work toward common understanding satisfactory to all (mutual understanding commitment); (2) a commitment to frame questions and propositions in ways that allow evidence to be brought to bear on them (empirical testability commitment); (3) a commitment to expand the body of collectively valid propositions (expansion commitment); (4) a commitment to allow any belief to be subjected to criticism if it will advance the discourse (openness commitment) (p. 7). Discourse moves associated with the realization of those commitments were determined during a first pass through the video transcripts; these moves were then given function codes that appear in Table 2.

Table 2 Function codes used in the move-level discourse analysis
Progressive Discourse Commitment Function Codes Code Abbrev. Used
Mutual Understanding 1. Request // Give Clarification/Elaboration Req. // Give C/E
2. Request // Give Re-explanation Req. // Give Re-expl.
Expansion 3. Request // Give Idea/Proposal Req. // Give I/P
4. Request // Give Alternatives Req. // Give Alt.
Openness 5. Request // Give Justification Req. // Give Just.
6. Request Evaluation Req. Eval.
7. Support // Modify // Refute Idea/Proposal Sup. // Mod. // Ref. I/P
8. Support // Modify // Refute Reasoning Sup. // Mod. // Ref Reas.
Empirical Testability 9. Request // Give Prediction Req. // Give Pred.
10. Request // Give Observations Req. // Give Observ.
11. Request // Give Analysis of Results Req. // Give Ana. Res.
Re-Utterance 12. Re-Utterance RU

It should be noted that the twelfth code—Re-Utterance—was not derived from the principles of progressive discourse, but from the discourse pattern known as revoicing which was explored by O'Connor and Michaels (1993, 1996). While revoicing is a three-move exchange, the re-utterance code developed from it for this study was applied to a single move based on a criteria O'Connor and Michaels established for identifying examples of revoicing: One of the moves must represent a re-stating of a previous speaker's content by a later speaker—usually in close adjacency (temporally) to the previous speaker's turn and often with some amount of re-formulation. This criteria lead to the definition of the re-utterance code: a move in which one speaker re-states all or part of a previous speaker's utterance in a manner which contributes to a deeper understanding of the original utterance or a deeper scrutiny of its content.

A graduate student was enlisted to check the validity of the function codes and determine inter-rater reliability. After several training sessions, the graduate student was given randomly-selected portions of transcript (each representing an entire task segment) to code; these portions contained 407 of 1535 total moves from the data corpus—or 26.5% of the coded data. The graduate student and the author matched on their codes for 347 of the 407 moves—equivalent to 85.3% agreement which is above the 80% considered as acceptable in this kind of analysis (Marshall and Rossman, 2006). The moves on which they did not match were reviewed, which supported the clarification of the code definitions and the refinement of the coding process.

Presentation of the data

The core of the data to be examined will be transcript excerpts chosen to be representative of the key discourse practices used by the teachers as they interacted with students in the initial explorations of students' ideas. In order to facilitate the interpretation of those excerpts and the identification of the practices they signified, it will be valuable to gain some insight into the teachers' views on effective science pedagogy. An appropriate source for providing a glimpse into those views was the teachers' responses to one of the main questions (Rubin and Rubin, 2005) from the first pre-lesson interview: ‘Researchers in science education often talk about the importance of engaging students in meaningful science dialogue; what would meaningful science dialogue look like in your classroom?’ Passages which captured the central idea in each teacher's response to that question are presented in Table 3.
Table 3 Quotes from teachers about ‘meaningful dialogue’
Teacher Interview Passage and Page from Transcript
Hannah “So, I think, um, them expressing—first of all—to each other what they think and then… but then building off of each other and sort of… I imagine it sort of as like them working through a problem together and so one student may be presenting something and then they take part of it and make it better.” (p. 2)
Marty “One of the things that I kind of… have… I don't know—‘adopted’—I guess—and it drives my students nuts, at least for the first month or two—is, if they ask a question, uh, I don't give like, a direct answer, per se. Like, on a homework, if they-… they’ll say, ‘I don't know how to do this’ or ‘What do I do?’, and almost every single question that I answer is with a question.” (p. 3)
Nancy “To get the questions to lead them through to something—not just like, ‘What's the answer to five?’, and, you know, they say, ‘Thirty-four.’ I mean, not in that sense, but in terms of, ‘Well, what do they mean by that?’ and trying to get that back-and-forth kind of thing.” (p. 4)
Sandy “I like the partner quizzes because they actually will discuss the information with their… their group. So, I like that because we don't get a lot of that discussion in how I normally teach class.” (p. 2)
Sarah “Um, meaningful dialogue to me means that you're giving them a little and then they're giving you something to work with and then you give some and then they… I mean, it's a two-way thing. It isn't just like, ‘Teacher standing up and telling students what it is.’And I think that, too, is also tough because you have to understand it in multiple ways—in multiple different forms to be able to do that effectively.” (pp. 6–7)

One of the insights which can be gleaned from these passages is that three of the teachers (Hannah, Nancy and Sarah) all considered allowing students to contribute significantly to the knowledge-building process (Bereiter and Scardamalia, 1993) as being a critical component of meaningful dialogue. It should be noted, however, that whereas both Hannah and Nancy showed confidence in being able to incorporate that component into their discourse practices, the second half of Sarah's passage indicates that she questions her self-efficacy (Azar, 2010) in this regard. Marty's response suggested a view of meaningful dialogue in which the teacher engages in a Socratic dialogue with students and forces them to take full ownership of the cognitive work of solving a problem; it should be noted, however, that this perspective specifically referenced a situation in which students had previously been confronted with similar problems. Finally, Sandy's response displays a tension between what she recognizes as an important aspect of science classroom discourse—significant student-student interactions—and what she is willing/able to incorporate into her regular classroom routine.

Through their replies to the question about what constitutes meaningful dialogue, all of the teachers have shown a recognition that this must involve allowing students to contribute in substantive ways to the process of idea exploration; they differ in their sense of how such substantive contributions might be structured and in their confidence in their capacity to provide that structure. These similarities and differences should be taken into account as the transcript excerpts presented on the pages that follow are examined for their implications relative to the research question.

Each excerpt in the set to be reviewed will contain the dialogue in a sequence or sequences. The dialogue will be presented as a series of speaker turns with each turn numbered according to its timing in the larger transcript and with each speaker identified by either a name (for the teachers) or a generic designation (for the students, such as MS 9 indicating that the speaker was a Male Student who was the 9th student to talk in that lesson). The speaker's identification is followed by her/his utterance, with various features of that utterance noted by a set of transcription conventions (see Appendix A). Finally, to the right of each utterance are a pair of codes which denote, first, the move type, and, second, the function code as explained in the previous section. If one of the twelve function codes was not applicable to a particular move, the second slot will be left blank.

Given that the data corpus from this project included 503 pages of video transcripts, a justification must be provided for the limited set of excerpts to be presented below. While the larger goal of this line of inquiry is to understand the overall process of how teachers lay down the language trails between students' ideas and those of science, this study is focused on the nature of the first steps which are taken along those trails. As a result, all of the excerpts were drawn from the Sharing Out Solutions task segments of the lessons, when students first offered their proposals for public consideration and teachers first indicated what possible pathways for building off of those proposals they might be considering. The selection of excerpts can also be substantiated based on the fact that, since they were taken from similar points in the sequence of actions within each lesson, comparisons between the teacher participants will be easier to make.

Excerpt 1: The first excerpt is taken from Nancy's period 6 (‘regular’ chemistry class). Prior to the videotaped lesson, the students had learned about types of chemical reactions and balancing equations; the videotaped lesson was used as an introduction to a unit on the mole and stoichiometry. The excerpt offered occurs at the beginning of the Sharing Out Solutions segment after Nancy had given the students less than two minutes to generate their proposals…

  Sequence 6    
71. Nancy: (MS 9), what did you say? How much do you think? I Req. I/P
72. MS 9: ‘6.54 grams’. R Give I/P
73. Nancy: ‘6.54 grams’. [5 s pause while she gets new marker to write on board and writes this value down under ‘S’] S::o he wants me to try ‘6.54 grams’. And why do you say that, (MS 9)? F  
I Req. Just.
74. MS 9: Because they [Zn and S] both have [charges of] two: one's plus two, one's minus and I just reduced the numbers. R Give Just.
75. Nancy: Okay. So if they go together in a one-to-one ratio, the masses go together in a one-to-one ratio. Okay. F RU

One key thing to note in this sequence is that Nancy follows the initial exchange (71–73) in which she gives MS 9 the opportunity to offer his proposal with a second exchange (73–75) in which she asks MS 9 to validate that proposal. This second exchange allows her to uphold Bereiter's openness commitment by subjecting a student's idea to [a first level] of critical evaluation. A second key thing to be cognizant of is that, immediately after a brief pause, Nancy begins the next sequence by saying, “Okay, well let's try it” (line 76), which signals a transition into the Conducting the Test task segment. The significance of this is that noticeably missing from the dialogue here is any request for alternative proposals which would have supported Bereiter's expansion commitment: As soon as the first proposal is justified, Nancy accepts it and elects to transition into the empirical test of that single proposal. This same pattern of discourse moves and concomitant classroom actions took place in her period 3 (‘honors’ chemistry) class.

Subsequent to the test of the initial proposal (which produced a less-than-desirable result), Nancy gave the students some time (a little over two minutes) to develop a new proposal(s). Following this second period of idea generation, Nancy states, “All right. So, I've got a couple of different people with a couple of different ideas, so let's get them all.” By comparison to the excerpt offered above, in this utterance, Nancy indicates her intention to uphold the expansion commitment by making sure that all of the alternative proposals are presented and discussed. As each of the [three] alternatives is offered, Nancy maintains her adherence to the openness commitment by making requests for elaborations or justifications. Again, this same pattern was observed in her period 3 class. The question evoked by this excerpt which must be answered in the next section is, ‘Why did Nancy ignore the expansion commitment initially in her two classes (by not using a request-for-alternatives move), but then attend to it later in both of the lessons?’

Excerpt 2: For this sample of data, two different sequences from Sandy's period 7 [heterogeneously-grouped] chemistry class will be provided so that some comparisons of Sandy's interactions with different groups can be made. Sandy's classes had covered the same material prior to this lesson which Nancy' students had. As further background to this excerpt, it is necessary to point out that in Sandy's other two classes, the same pattern of discourse moves just described in Nancy's classes were observed: There was an initial request for proposals, followed by an initial proposal of ‘6.54 grams’, a request for justification and a giving of justification—followed by a movement into the empirical testing phase. As in Nancy's lessons, there was no request for alternative proposals made prior to conducting the first test.

A final note relative to the context of the lesson from which these sequences were drawn: Because of a school event which had occurred, the zinc-sulfur-reaction lesson was conducted in Sandy's period 7 class the day after it was completed in her other two classes. In a post-lesson interview, Sandy indicated that, the morning of this lesson, she realized that she had wanted to structure the Generating Solutions task segment differently than she had done on the first day: “And I thought I was going to say, ‘Okay, I want you to come up… I'm going to give you a number and I want you—you know, you're going to have a partner—and you're going to come up with an answer’” (Sandy, Interview 3, p. 2). The result of this realization was that period 7 was the only class in which multiple proposals were offered before the test was conducted. The reader is asked to consider the way Sandy responds to these different proposals—specifically by paying attention to the nature of her second initiation move in each sequence…

  Sequence 4    
37. Sandy: All right. [Pointing to group to left] So what do you think? I Req. I/P
38. FS 2: ‘3.22’ R Give I/P
39. Sandy: ‘3.22’. F  
  Why? I Req. Just.
40. FS 2: I don't know. R  
41. FS 3: That's just what we came up with. [Laughs while saying this.] R  
  Sequence 5    
42. Sandy [Pointing to group near middle lab station]: What do you think? I Req. I/P
43. MS 4: We're going with the same amount. R Give I/P
44. Sandy: Same amount. F  
  ‘6.54’? I Req. C/E
45. MS 4: [Nods his head] R Give C/E
46. Sandy: Yeah [indicating she has correctly interpreted ‘same amount’]. F  

What the reader should notice is that, in her second initiation move in sequence 5, Sandy does not make a request for justification as she does in sequence 4; she likewise does not make a request for justification when the third idea is proposed. Two sequences later (sequence 7), she reviews the ideas that the three groups have offered and, once again, only makes a request for justification of the group that suggested ‘3.22 grams’ (approximately equivalent to the accepted solution to the problem). Then, after a side conversation takes place between the members of the group proposing this idea, Sandy begins sequence 9 with the following utterance:

75. Sandy: Okay. Now, we have to… choose one amount, okay, to run our demo. Is there any amount that you can say, ‘Uh, I don't think we're going to use that amount?’

Interestingly, the first idea to be removed as an option for conducting the initial test upon was the ‘3.22’ gram proposal—corresponding to the normative solution. This was likely a result of the fact that Sandy had twice asked the group suggesting this amount for a justification, and they were not able to give a scientific justification in either instance. In the end, the class settled on the equal-mass proposal (‘6.54’ grams) to test first. During the post-lesson interview, as the author was trying to gain Sandy's perspective on the kind of thinking in which students engaged in her enactments, it became clear that this is exactly the way Sandy wanted things to proceed:

Researcher: Were you surprised by the thinking they went through? Were there any people that made contributions that you might not have expected them to or…?

Sandy: No, I don't think so. I think it was mostly what I expected—what I expected they would do. I think it was what I expected they would do [with me] doing it differently [than she had covered this topic previously]—except for the three different values in that [Pd. 7] class. When that happened I was like, ‘Okay, gotta think, gotta think, gotta think.’

Researcher: So that was a really important moment for you—you were really caught off guard by that?

Sandy: Yeah. I was just [like], ‘Okay, now what… How am I going to get them to pick one?’ And I didn't… I was thinking, ‘How am I going to get them to pick the same amount [of sulfur as zinc]?’

Researcher: Oh, so you wanted them to pick the same amount?

Sandy: I wanted them—the first time I wanted them to, because I wanted it to go wrong.

This interview segment makes very clear that the goal of the discourse moves which Sandy employed was to funnel the students' thinking towards a focus on the solution (‘6.54 grams’) associated with an alternative conception related to stoichiometry (that the coefficients in the balanced equations represent a mass ratio rather than a mole ratio). A second question to be addressed in the next section is, ‘What is the significance of the fact that Sandy intentionally steered students towards choosing the non-normative answer to conduct the first test upon?’

Excerpt 3: Sarah's [honors] chemistry classes had a different background at the onset of the lesson than either Nancy's or Sandy's classes had: Whereas Nancy and Sandy had chosen to use the zinc-sulfur-reaction lesson as an introduction to the mole concept, Sarah had decided it to use it as a review of that concept after completing part of a unit on stoichiometry. Because her students had this more extensive background, Sarah elected to use a different given amount of zinc (13.00 grams) than the other teachers had employed—one that would challenge the students more to apply the ideas they had recently been taught.

The single sequence displayed below transpires towards the end of the Sharing Out Solutions task segment in Sarah's period 3 class; this segment generally had a greater duration in Sarah's classes than it did in Nancy's and Sandy's classes because students actually presented some calculations as part of their justifications. While reviewing this sequence, the reader should note that, whereas ‘6.4 grams’ represented a value associated with an alternative conception in Nancy's and Sandy's classes, here it corresponds to the normative solution…

  Sequence 25    
171. Sarah: Um, do you suggest we try ‘6.4 grams’ of sulfur, or is there I  
  another solution that's out there that you guys want to test? I Req. Alt.
172. Unknown male student: Yeah, ‘6.539’. R Give Alt.
173. Sarah [ignoring this suggestion]: How many people want to try ‘6.4’? I [repeated]  
174. [No apparent response] R  
175. Sarah: How many people would rather try ‘13 grams’ and ‘13 grams’… of sulfur—‘13 grams’ of zinc and ‘13 grams’ of sulfur? I Give Alt.
176. [FS 1 raises her hand] R Sup. I/P
177. Sarah [pointing to FS 1]: You wanna try that? That's probably a good idea. [Writes that down on transparency] So we'll try both. F  

Of great significant here is the fact that, compared to Nancy and Sandy, Sarah did utilize a request-for-alternatives move (therefore supporting Bereiter's expansion commitment) prior to transitioning the class into the initial testing phase. What is most intriguing about this is that it was Sarah herself who [eventually] proposed a different amount to test: one tied to the alternative [equal-mass] conception (in her second initiation move, line 175). Sarah did this in her period 7 class as well—in that case after the test on the normative solution proposed by the students had been conducted. In the other two classes, students themselves offered this proposal; in one case, the proposal was forwarded in the Sharing Out Solutions segment and in one case it was suggested after the first empirical test had been completed. This set of circumstances leads to the question, ‘What prompted Sarah to interject her own proposal [of the equal-mass solution] in the cases where the students did not develop this idea?’

Excerpt 4: Hannah's students came into the zinc-sulfur-reaction lesson with a similar background to Nancy's and Sandy's students. Hannah generally, though, approached the structuring of the Generating and Sharing Out Solutions task segments differently from Nancy and Sandy (as well as from Sarah). In fact, the activity structure (Polman, 2004) which she implemented was more similar to the one used by Marty than the one utilized by those teaching the same lesson as her: During the Generating Solutions task segment, students were placed in their regular lab groups (as opposed to working with whomever they chose) and during the Sharing Out Solutions segment, all groups were expected to present their proposals (as opposed to allowing students to volunteer their ideas). The passage to be examined from Hannah's lessons came from her period 3 class when the last of the six groups was offering its solution…

  Sequence 19    
68. Hannah: Okay, up here [front left corner group], girls, what are you thinkin'? I Req. I/P // Req. Just.
69. Unknown member of group: Who should…? I  
70. Hannah: Whoever. R  
71. FS 18: Um, well we knew that ‘65.4’ was the atomic mass of zinc, and ‘32.1’ was the atomic mass for sulfur, so we just moved the decimal to the left because it [the hand-out] said the zinc to start was like ‘6.54’—so that moved the decimal. So we got the atomic mass of the other one [sulfur] and moved the decimal to the left. R Give I/P // Give Just.
72. Hannah: Okay. I just want us to hear that one more time because F  
  a couple of people looked like maybe they’re not following. Let's try (FS 19). (FS 19), can you do the same exact explanation? I Req. Re-Expl.
73. FS 19: Um… zinc's atomic number—or, atomic mass is‘65.4’… R Give Re-Expl.
74. Hannah: On the periodic table, you mean? I Req. C/E
75. FS 19: Yeah. R Give C/E
76. Hannah: Okay. F  
77. FS 19: And then sulfur's was ‘32.’ [pause while she checks paper]… ‘.1’. And then just… and you said the most we could use was ‘65.4’ [meant‘6.54’]—which is moving the decimal over to the right. [Cont. R from 73]  
78. Hannah: Okay. F  

The key discourse event occurs in turn 72 when Hannah conducts a request for re-explanation, a move which supports Bereiter's mutual understanding commitment by having the front right group's proposal re-presented by another member of the group. What makes this event noteworthy is that Hannah only used this move twice in her set of enactments: Both times it was associated with the exposition of the scientifically-accepted solution; she never utilized this move in conjunction with the discussion of a non-normative proposal. In the one class (period 1) where she did not employ a request for re-explanation when the scientifically-accepted solution was offered, Hannah gave the only positive evaluation of a proposal that was identified in her lessons. Using this move only in relation to the proposals which were aligned with the scientific answer suggests a need to consider the issue, ‘What are the pedagogical implications of discourse practices which might foreground some ideas and background others?’

Excerpt 5: This final excerpt is taken from Marty's period 6 [honors] chemistry class. It should be recalled that Marty picked a different problem to pose to his students: one based on the predicted patterns in atomic radii down a family and across a period. Much like Hannah, Nancy and Sandy, Marty had chosen to use the activity associated with this lesson as an opening to a unit—in his case, one on trends in periodic properties. Prior to the lesson, students had learned about the Bohr model of the atom (as they used Bohr model diagrams to help in making their predictions of the patterns) and about the format of the periodic table.

As noted in the background to the excerpt from Hannah's lesson, Marty used an activity structure different from Nancy, Sandy and Sarah in that students were placed in their regular laboratory groups to complete the lesson's objectives and each group was required to share their solution with the rest of the class. Because of this, it was easier to detect patterns in the way that Marty responded discursively to the solutions offered by his students, much as was the case with the dialogue from Hannah's similarly-structured enactments.

It is important to preface the presentation of the relevant data from Marty's period 6 class with a passage from his second pre-lesson interview. It occurs at a point in the interview where Marty is describing some aspects of his planned enactment of the lesson…

Researcher [following up on a previous thought]: Like, when they have this discussion, are they going to present to each other and…

Marty: Well I think… Like, the group… like if you and I were a group we'd have to come up with one conclusion and write that down. And then I'm going to, you know, say, ‘Can you share…’

Researcher: With the other groups.

Marty: ‘…with all of us what was your order and why you put it in that order?’

Researcher: Okay.

Marty: And it'll be a little different because each one will have a different family. So hopefully, they’ll see that that relates to every other one.

Researcher: Good. Okay.

Marty: Um, and then the next one, I'm going to have them do the period. And I think that's going to cause some problems because they're [the electrons] all going to be in the same ring and if it goes by what I've seen previously, I think probably half of them are going to have the trend incorrect. Because I think they're going to see…

Researcher: Will they say it's equal size or will they say that it's larger across?

Marty: I think they're going to say that it's larger across because, ‘Oh, we put more electrons in there, just like we did in the other one, so it's got to get bigger.’ And, maybe a couple will say that they're all the same size. I'm not… I don't think that's going to be true, but I guess we'll see.

The key insight to glean from this excerpt is, in anticipating students' thinking (Stein et al., 2008), Marty had developed the expectation that his students would correctly predict the trend in atomic radii down a family, but would most likely get the trend across a period incorrect—in fact, his expectation was that they would predict the opposite trend (size increases instead of decreases). The existence of this expectation should be kept in mind as a pair of excerpts from Marty's period 6 class is considered. The first is from the segment where the groups are Sharing Out their trends down a family and the second is from the segment where they are Sharing Out their trends across a period; in both cases, it is the same group that is presenting its results. While examining these two excerpts, focus on the second exchange in each sequence…

  Sequence 16    
119. Marty: How about… the Carbon family—anyone? I  
120. FS 4: That was us. R  
121. Marty: Okay. F  
  Instead of going through all of them [elements in the family], do you have the same exact trend as you went down—they got larger? I Req. I/P
122. FS 11: Yep. R Give I/P
123. Marty: Same trend. F  
  Why? I Req. Just.
124. FS 11: We figured that as long as electron rings are the same size, then more rings equals a bigger atom. R Give Just.
125. Marty: Okay. So as long as the rings are all the same size, the more rings, the larger the atom—or, the more orbits, the larger the atom. F RU
  And…    
  Sequence 25 [picking up after a pair of preparatory exchanges]    
163. Marty: What's your smallest element? I Req. I/P
164. FS 4: Um, rubidium. R Give I/P
165. Marty: And your largest? I Req. I/P
166. FS 4: Neon. R Give I/P
167. Marty: So they say that the trend gets bigger as you go from F RU
  left to right. Is that what you're saying? I  
168. FS 4: Yeah. R  
169. Marty: Yeah. F  
  Why? I Req. Just.
170. FS 4: Um, there's more… more electrons, so it will be a bigger atom. R Give Just.
171. Marty: More electrons makes the atoms larger. F RU
  Seems logical also. [Appraisal]  

The key discourse feature is something which is found in Marty's final turn in the second sequence [line 171], but is absent in the equivalent turn in the first [line 125]: an appraisal of the justification. In sequence 25, this appraisal serves as a form of foreshadowing: It signals the fact that even though the justification “seems logical”, the students will later find out that it is not. The reader should notice that Marty's appraisal in 171 ends with “also”—indicating that he has made a similar evaluation previously. In fact, within this lesson, in four of the six sequences during the Sharing Out segment for the trend across a period—a trend Marty expected the students to predict incorrectly—such an appraisal is present. In the two cases in which there was no such appraisal, there were disruptions in the discourse pattern that caused Marty to not close out the sequence with the same follow-up move observed in the sequences above. Further, such appraisals do not appear in any of the sequences during the Sharing Out segment for the trend down a family—a trend Marty expected the students to correctly predict.

In his period 4 class, such individual appraisals at the end of each sequence were not present. Instead, in the final turn of the Sharing Out segment for the trend across a period, a collective appraisal of the justifications offered was made by Marty and, again, it was done in a way as to foreshadow that the students' logic, while understandable, will be proven by empirical tests (atomic radii data from a web site) to be flawed: “So, all of your reasons are legitimate… they all happen, they're all trends in the periodic table. Now, what you are going to do is to check and see if that is actually correct or not” (turn 219). No such collective appraisal appeared at the end of the Sharing Out segment for the trend down a family. As with the highlighting noted in the excerpt from Hannah’s lessons, this raises the issue of the pedagogical significance of engaging in such discourse practices—an issue to be addressed in the next section.4

Discussion of data

The purpose of this study was to discern the features of the discourse structures which emerged as teachers facilitated conversations around two problems posed in introductory high-school chemistry classes. One of the most readily-apparent features found in the data (both the limited set of excerpts presented and the larger corpus) was not considered explicitly in the last section but was visible in the coding. It is a pattern of classroom discourse first identified by Coulthard (1977) and Mehan (1979) and much discussed—and maligned—in the educational discourse literature (e.g.Alozie et al., 2010; Cazden, 2001; Lemke, 1990): The three-part exchange involving a [teacher] initiation, a [student] response, and a [teacher] evaluation (or feedback or follow-up) which has been labeled the IRE (or IRF) sequence. Lemke (1990) examined this practice in detail and criticized it heavily because of (1) the miscommunications (p. 28) and (2) power asymmetry (p. 44) it can produce. He suggested other discourse patterns—such as student questioning dialogue (p. 52) and joint construction (p. 104)—which could mitigate these issues by allowing students to take ownership of the I and E/F moves.

One reason that the prevalence of the IRE/F pattern with teacher-dominated I and E/F moves was not made explicit was that this finding has been so thoroughly documented that noting its existence would contribute nothing to the chemistry education literature. Another reason is that, as Nassaji and Wells (2000) have argued, it is not this exchange pattern itself which is inherently effective or ineffective as a discourse practice; it is the content of each turn in the sequence, as well as what follows such an exchange, which determines whether or not this practice facilitates deeper understanding of the topic. For instance, Nassaji and Wells point out that if the teacher's initiation turn involves questions which “introduce issues as for negotiation,” then this is more likely “to elicit substantive student contributions” (p. 400). Likewise, if the teacher's follow-up turn “requests justifications, connections or counter-arguments,” then the power asymmetry is diminished and the dialogue adopts “a more conversation-like genre” (p. 401) where the IRE/F sequence is the nucleus of a more extensive set of dialogic interactions.

Following the lead provided by Nassaji and Wells, noting the frequent occurrence of the IRE/F pattern in the lessons analyzed is only a precursor to exploring the more relevant issue, ‘Along what pathway(s) did the use of this exchange sequence lead the participants in these conversations?’ In order to address this issue, a review of the main points made from the analysis of each lesson excerpt is in order: (1) Nancy’s extract showed that she did not use a request-for-alternatives move following the offering of a proposal related to a common alternative conception; (2) the set of sequences from Sandy's classes made apparent that, in the one class in which more than one proposal was made initially, Sandy used her feedback turns to insure that it was the proposal associated with the alternative conception which was chosen for testing first; (3) the selection from Sarah's lesson illustrated her concern for interjecting the solution based on the alternative conception in the case where students did not do so; (4) Hannah's excerpt illustrated her use of a unique discourse move (request for re-explanation) to highlight the scientifically-accepted proposal; and (5) Marty’s passage depicted the utilization of his feedback turns to foreshadow which ideas would be proven invalid through examination of empirical data.

What generalizations related to the question posed above can be abstracted from this review? In the case of Nancy's, Sandy's and Sarah's lessons—where a limited set of proposals was to be presented and tested—the I and E/F moves employed by these teachers clearly had the purpose of either insuring that the most likely alternative conception would be tested empirically first (in Nancy's and Sandy's enactments) or that this alternative conception would be considered for testing in the event that it was not the solution towards which students' initially gravitated (in Sarah's enactments). In the case of Hannah's and Marty's lessons—where each group was expected to offer a proposal and all of these proposals would be tested—the I and E/F moves served the purpose of highlighting either those solutions which would be shown to be correct (in Hannah's enactments) or those that would be shown to be incorrect (in Marty's enactments) prior to testing. In summary, the purpose of the set of discourse moves made salient in the previous section was to prime the students psychologically in such a way that the results of the empirical tests would very clearly produce a strong sense of dissatisfaction or satisfaction with their ideas—particularly, dissatisfaction with the ideas related to known (by teachers) alternative conceptions.

Chemistry educators will recognize that the purpose just ascribed to the discourse practices of the teachers involved in this study is in accordance with the starting point of the classical conceptual change approach developed by Posner et al. (1982). Drawing on the work of Piaget (1975) and Kuhn (1969), Posner et al. suggested that the first step in the pathway to accomodation—or concept replacement, the goal of their model—is to create cognitive conflict. This, of course, is followed by efforts to support students in viewing the scientific concept as being intelligible, plausible, and fruitful. While the logic of this framework is compelling, its effectiveness has been questioned on both empirical and theoretical grounds. In her review of research in this area, Limón (2001) identified a number of studies that cast doubt on the merit of this approach (e.g.Dreyfus et al., 1990; Dykstra et al., 1992). Further, after showing some positive results from her own work with the use of this strategy in science classrooms, she concedes, “…perhaps the most outstanding result of the studies using the cognitive conflict strategy is the lack of efficacy for students to achieve a strong restructuring and, consequently, a deep understanding of the new information” (p. 364). From a theoretical standpoint, Smith et al. (1993) opined “that many of the assertions of misconceptions research [and the classical conceptual change model which prompted it] are inconsistent with constructivism” (p. 123).

Using the data from this study, it is possible to consider several limitations of the traditional cognitive conflict approach in moving students between their initial ideas and those of science. First, the teachers' responses to the question of what constitutes meaningful dialogue indicated that all of them recognized a need to have students participate substantively in the conversation associated with idea exploration during lessons like the ones analyzed, and three of them (Hannah, Nancy and Sarah) suggested that students should contribute significantly to the conceptual progress of the discourse. However, eliciting certain ideas with a singular objective of setting them up to be proven invalid does not support the achievement of the outcomes these teachers promulgated. A second and related limitation is that engaging in this practice on a regular basis creates what Linnenbrink and Pintrich (2002) called affective resistance in students, where students become less willing to offer their ideas due to the recognition that those ideas are being elicited in order to show that they are logically flawed. That this point had been reached in at least one of the classrooms was evident from an exchange in Nancy's period 3 class. Right before the testing of the initial (equal-mass) proposal, FS 5 states, “I feel like she's going to prove us wrong” (turn 122). When Nancy somewhat facetiously asks, “Have I ever done that to you before?” (turn 123), several students reply, “Yeah” (turn 124).

A third issue with the traditional cognitive conflict approach as it was embodied in the set of lessons reviewed is that there is a rapid succession of events from extracting students' ideas, to using discourse in some way to mark them as ‘correct’ or ‘incorrect’ to using data or observations to test those ideas in order to show which were correct or which were incorrect. Such a pattern may send the message to students that empirical testing is the only mechanism for vetting different ideas in the process of scientific inquiry. A concern in this regard was raised by Hammer and Van Zee (2006). Recounting a workshop discussion related to a video of third-graders exploring the nature of bubbles produced by different-shaped bubble wands, they noted that several teacher participants felt the conversation in the video should have been cut shorter so that the students could conduct a test of their ideas. In reflecting on this, Hammer and Van Zee comment, “It [the suggestion that the conversation should have been discontinued] may reflect a view of children or of science that empirical tests are the only way to make progress” (p. 127).

Another concern raised by Hammer and Van Zee is that teachers utilizing the cognitive conflict approach tend to hear students' ideas in terms of a simple dichotomy of ‘right’ or ‘wrong’ instead of listening carefully to the different components of those ideas in order to build up a “menu of possibilities” (p. 41) of how to respond to them. As a result, the use of this strategy lays down a very linear and narrow language trail, preventing teachers and students from branching out into uncharted territory that may broaden and deepen the conceptual understanding of all of those involved in the discourse. Related to this, the cognitive conflict approach does not provide a realistic model of how scientific progress most often occurs—with its wrong turns, dead ends, and multiple pathways towards more profound insights about nature (Bauer, 1994; Goetz, 2007). That teachers—such as those participating in this study—continue to use the cognitive conflict approach despite the criticisms outlined above is not in and of itself an issue as it certainly has its place in the chemistry classroom. That it was the only approach used by the five participating teachers is a reason for concern—a subject to be addressed in the last section.

Implications and conclusions

So what is the message that members of the chemistry education community should take with them from reading this study? Is the point that ineffective practices are being used by under-performing teachers? Absolutely not. Much like the IRE/F sequence, the cognitive conflict strategy is not inherently bad or good. If it is used in conjunction with other approaches to prompt students to re-examine their understandings of scientific phenomenon and to promote progressive discourse around the explanations for those phenomenon, then it can be a useful tool in a larger pedagogical toolkit. However, it cannot be the only tool in the toolkit, and the data from this study—not just the excerpts which were presented, but also interview data where teachers and students were asked a question about how typical the nature of the talk in each lesson was—suggest that it is the strategy used almost exclusively by these teachers. This suggests that more attention needs to be given in teacher preparation programs (the participating teachers represented the top three programs in the state of Pennsylvania in terms of numbers of science educators produced) and in professional development experiences as to how to facilitate meaningful science talk. The frameworks (Accountable Talk and Heuristic for Progressive Disciplinary Discourse) discussed earlier in the paper provide strong foundations in this area. Nonetheless, these frameworks focus on guidelines relative to the norms of effective science talk, but not how to realize those norms in the “bumpiness” of open-ended conversations (Varelas and Pineda, 1999). Supplementing those frameworks with sets of principles such as the five practices for orchestrating productive discussions identified by Stein et al. (2008) could provide teachers with a more holistic schema for laying down more enriching language trails.

Further, all of the teachers who participated in this study were regarded by their administrators, colleagues, students (as came through in student interviews), and this researcher as quality chemistry teachers. Nonetheless, three of the participants—Nancy, Sandy and Sarah (representing a range of years of experience)—expressed clear trepidation about facilitating an open discussion with their students. The following statement from Sarah’s second pre-lesson interview was reflective of this and spoke to the root of that fear: “But, you have to… you have to let go of just knowing exactly how the lesson's going to go, because kids are going to say different things.” The uncertainty of ‘letting go’ of the direction of both the conversation and the lesson is likely to be unsettling for most teachers, and adopting a cognitive conflict schema—with its linear pathway from students' alternative conceptions to science's accepted conceptions—can help mitigate some of that uncertainty. One way to move teachers past reliance on this strategy is to provide opportunities in both teaching methods courses and professional development activities for teachers to engage in video reflection (e.g.Sherin and van Es, 2009) which may help them develop a ‘menu of possibilities’ (Hammer and Van Zee, 2006) for paving pathways between students' ideas and those of science.

Some of the suggestions for helping teachers expand their repertoire of discursive practices were employed by the author as the work with the teachers introduced in this study moved into its second year, and the impact this had on the way these teachers structured the science talk will be described in future papers. Nonetheless, there is a recognition that more work needs to be done in this area by members of the chemistry education community. This author has expanded his own project by obtaining video from teachers in urban settings working with more diverse student populations and by collecting survey data about teachers' preferred strategies for promoting conceptual change. Still, it is essential that other researchers contribute to the broader exploration of this issue in order that the relationship between teachers' views of conceptual change and their discourse practices can be more fully understood and that multiple perspectives on how to support teachers in constructing the most panoramic language trails towards chemistry literacy be considered. Without such support for teachers, students may continue to experience classrooms in which their degrees of freedom for exploring chemical phenomena are reduced.

Notes

1. The larger research project had been granted IRB approval by the author’s academic institution. All participants signed an informed consent document to allow them to be videotaped and audiotaped. Additionally, parents of the students signed informed consent documents for their son/daughter to participate in the data collection.

2. A valid concern was raised by a reviewer that having one teacher present a lesson with different content might make comparisons between the teachers untenable as the change in topic could lead to different discourse patterns. As will be shown, that teacher used the same discourse patterns for the lesson which will be discussed as he did with data collected a year later for the lesson conducted by the other four teachers. The decision to include the data from the periodic trends lesson is that it was collected the same year as the data from the other four teachers; thus, this limits length of participation in the study as a confounding variable in comparing the four teachers' discourse practices.

3. Wells defined a sequence as “a single nuclear exchange and any exchanges that are bound to it” (p. 236). This definition was found to be unsatisfactory in determining sequence boundaries and so a definition based on focusing on a single topic and maintaining a certain speaker configuration was adopted. With regards to the second criteria, it was found useful to mark a new sequence as being initiated if, for instance, a teacher was engaged in a dialogue with a single student over a topic and then switched to discussing that topic with the whole class.

4. Note 2 acknowledged a concern by a reviewer that using data from lessons in which different content was taught might impact the talk practices observed. The discourse move discussed in Marty's excerpt was one where he highlighted answers which he had expected to be incorrect and which met that expectation by adding an evaluation to his follow-up move. That same practice was observed in the 2nd year of data collection when Marty taught the zinc-sulfur-reaction lesson. For instance, after a student had proposed the equal-mass solution (a common alternative conception) in his period 4 class, Marty said, “That sounds pretty logical, right?” (turn 64).

Appendix A: transcription conventions

While there are a broader set of conventions used in the larger data corpus, here are the ones found in the data presented in this article:

1. If a student identification is placed in parentheses during an utterance [e.g. (MS 9) in the first excerpt], this indicates that the speaker specifically named that student. The parentheses and generic identifications were used to maintain the students' anonymity.

2. An ellipsis (…) either represents a short pause (of less than half a second) in the speaker's utterance or a change in direction of the speaker's line of thinking.

3. Italicized words indicate an emphasis on these words (i.e. by raised intonation) by the speaker.

4. If the pronunciation of a syllable was elongated beyond the amount of time a speaker would normally take to complete this, a pair of colons (::) was inserted in the syllable.

5. Overlapping speech was represented by a left carrot (<), with the word immediately after the carrot for the adjacent speaker turns indicating the point of overlap.

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