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 DOI: 10.3102/0034654311423382

October 2011 2011 81: 530 originally published online 25REVIEW OF EDUCATIONAL RESEARCH

Rebecca M. Schneider and Kellie PlasmanPedagogical Content Knowledge Development

Science Teacher Learning Progressions: A Review of Science Teachers'  

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Review of Educational Research December 2011, Vol. 81, No. 4, pp. 530–565

DOI: 10.3102/0034654311423382© 2011 AERA. http://rer.aera.net

Science Teacher Learning Progressions: A Review of Science Teachers’ Pedagogical Content

Knowledge Development

Rebecca M. Schneider and Kellie PlasmanUniversity of Toledo

Learning progressions are the successively more sophisticated ways of think-ing about an idea that follow one another over a broad span of time. This review examines the research on science teachers’ pedagogical content knowledge (PCK) in order to refine ideas about science teacher learning progressions and how to support them. Research published between 1986 and 2010 relevant to science teacher learning and PCK was examined for what ways teachers’ knowledge becomes more developed and what appears to be the sequence. Analysis indicates that it is helpful for teachers to think about learners first, then to focus on teaching, and points out the essential role of reflection for teachers to rearrange their ideas in ways that develop their PCK. This review takes a unique approach to thinking about research on what science teachers learn and can support teacher educators in design-ing professional programs that support beginning and advanced learning for science teachers.

Keywords: science teachers, pedagogical content knowledge, teacher thinking, teacher learning.

Introduction

Preparing quality science teachers is fundamental to ensuring students’ success (Carnegie-IAS Commission on Mathematics and Science Education, 2009; Darling-Hammond, 1999; National Commission on Teaching and America’s Future, 1996). Recognizing the importance of quality teaching, reformers are sug-gesting that preparation and continuing education programs for science teachers need rethinking (Hinds, 2002; National Research Council, 2000). Too often these experiences are disjointed and disconnected from each other and from classroom practice (Garet, Porter, Desimone, Birman, & Yoon, 2001; Goodlad, 1990). Yet if teacher educators are to develop more coherent and ongoing experiences and pro-grams, they will need a better understanding of how teachers’ knowledge of teach-ing grows and is connected from one set of experiences to the next. Only then will

423382RER10.3102/0034654311423382Schneider & PlasmanScience Teachers’ PCK Development

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experiences and programs intended to be educational deliberately support teach-ers’ ongoing learning.

Understanding how science teachers learn and continue to learn about teaching science is essential to creating programs to meet their needs at each stage of their careers. Learning progressions—although proposed as a framework to guide our thinking about student learning—can guide our thinking about how teachers’ knowledge progresses over time. For science teachers, a learning progression framework means considering teachers’ ideas and how they develop as teachers continue to learn about teaching science. Pedagogical content knowledge (PCK) is a construct to aid our thinking about what teachers continue to learn as they study their practice. To begin to understand how science teachers’ learning pro-gresses, the research literature relevant to science teachers’ pedagogical content knowledge was reviewed. By looking across studies that examine PCK at different points across preservice, new, continuing, and leader teacher career phases, this review will inform efforts to design teacher education programs that reach across a career and highlight areas for further research.

Theoretical Framework

Developing expertise in guiding students’ science learning is a challenging and ongoing process. Not only does it take time and guided practice to develop skill in guiding student inquiry (e.g., designing investigations and developing explana-tions), supporting collaboration, and incorporating learning technologies in ways that engage all students in actively constructing deep understanding of important science concepts (American Association for the Advancement of Science, 1993; National Research Council, 1996), teachers are also charged with supporting the diverse needs of students while preparing them to consider careers in science fields. The National Research Council (2007) has proposed four key goals for sci-ence learners: know and understand the natural world, generate and evaluate sci-entific evidence and explanations, understand how scientific knowledge is constructed, and participate in scientific practices and discourse. Learning to cre-ate active and engaging science learning environments is no simple task. Indeed, there is substantial evidence that teachers face many challenges as they learn about teaching science (Crawford, 2007; Davis, Petish, & Smithey, 2006; Marx, Blumenfeld, Krajcik, & Soloway, 1997). Science teachers need ongoing educative support as they learn how to create effective science learning environments with their students (Bianchini, Johnston, Oram, & Cavazos, 2003; Crawford, 2000). Matching teachers’ needs for learning support will depend on an understanding of how science teaching expertise develops over time.

Learning Progressions for Science Teachers

To think about teachers’ learning across their careers implies thinking about how ideas and skills of teaching become more refined over time. Primarily in refer-ence to student learning, learning progressions have been described as the succes-sively more sophisticated ways of thinking about an idea that follow one another over a broad span of time (Heritage, 2008; National Research Council, 2007). This framework also makes sense as we think about teacher learning, particularly since learning to teach is considered a career-long endeavor (Ball & Cohen, 1999; Borko,

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2004). It is reasonable to think about teachers becoming successively more sophis-ticated in their thinking as they spend time in the classroom and are supported by opportunities for learning and professional development.

The characteristics of learning progressions are that progress is: continuous and coherent, an incremental sequence from novice to expert performance, and medi-ated by instruction (Heritage, 2008). To think of learning as a continuous or devel-opmental process is not entirely new (e.g., see spiral curriculum [Bruner, 1960] or developmental corridors [Brown & Campione, 1994]). What is more recent is an emphasis on linking instructional planning and formative assessment in a progres-sion of learning (Heritage, 2008). For teachers, assessment of what beginning and advanced teachers should know and be able to do is at the forefront of discussion of teacher quality (e.g., see National Science Teachers Association standards for beginning teachers [National Science Teachers Association, 2003] and National Board standards for advanced teachers [National Board for Professional Teaching Standards, 2003]). These assessments, however, are based more on what is desired rather than what might be developmentally reasonable. The notion of learning progressions for teachers is also consistent with descriptions of what expert teach-ers are able to do and the stages of teacher development (Berliner, 1994). These descriptions are of teachers’ skills and based on comparisons of novice or inexpe-rienced teachers and expert or teachers with years of experience. The process of learning or what teachers know is not described, and the relationship of instruction for teachers to their developing expertise has not been examined. An understanding of how teachers’ knowledge progresses with instruction will fill critical gaps in our understanding of how to design opportunities for and assess teacher learning (Wilson, Floden, & Ferrini-Mundy, 2001).

Alignment with curriculum is also included by some as a characteristic of learn-ing progressions. One approach is the idea that learning progressions are bounded by assumptions regarding students’ initial ideas at one end and by what is expected at the other end of the progression (Duncan & Hmelo-Silver, 2009). Others describe research on learning progressions to be beneficial for improving curricu-lum based on a better understanding of students’ progress in relationship to instruc-tion (Corcoran, Mosher, & Rogat, 2009). In response to researchers using defined goals for student understanding as targets for thinking about the track of a learning progression, Shavelson (2009) cautions against aiming at specific, set goals. In addition, it is more helpful to think of learning progress as a trajectory of develop-ment rather than a series of discrete events (Heritage, 2008). For teachers, it is important to have a notion of expertise that requires sophisticated thinking. It is less helpful in the process of describing learning progressions for teachers to target specific ideas as end points in that development.

Developing expert knowledge. For teachers developing competence in teaching science, it is interesting to think about adaptive expertise. Adaptive experts are those who relish challenges and are continually looking for ways to stretch their knowledge and abilities as they develop new habits of mind, attitudes, and ways of thinking (Bransford, 2001). These experts are able to tolerate ambiguity and let go of previously held assumptions as they engage in learning new skills and knowl-edge. Juxtaposed to adaptive expertise is routine expertise, where these experts are

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skilled in applying known routines that they have developed over time. These experts continue to learn, but learning is focused on becoming more efficient at carrying out those routines and hence they perform well in a stable environment. Adaptive experts are much more likely to evolve their core competencies and con-tinually expand the breadth and depth of the expertise as the need arises or as their interest demands. This often requires them to venture into areas where they must function as “intelligent novices” who often struggle initially in order to learn new things (Bransford et al., 2006). Adaptive expertise requires relatively sophisticated ways of thinking about teaching and is a constructive outcome of teachers’ learning progress.

Applying learning progression as a framework to think about teachers’ develop-ment will mean describing trajectories from novices to adaptive experts. Although adaptive expertise is a relatively recent refinement of the idea of expertise, thinking about trajectories can be guided by what is known about the development of exper-tise. The development of expertise is considered a long-term endeavor that takes about 10 years (Ericsson, Krampe, & Tesch Romer, 1993). For teachers specifi-cally, Berliner (2001) suggests expertise takes more than 5 years, if it does develop. Based on novice–expert work, Berliner (1988, 1994) describes five levels of skill development: novice, advanced beginner, competent, proficient, and expert. Although continued and steady development cannot be assumed, Berliner’s stages are somewhat similar to preservice, induction, midcareer, and advanced-career years that are often used to describe teachers’ experience. What is interesting is that many expert–novice studies included what were called postulant teachers. These teachers were content experts but novice teachers and were used to illustrate the development of pedagogical knowledge independently of content knowledge. An additional career phase used to describe teachers is the teacher leader or mentor teacher stage. Teachers who take on the role of leader or mentor are considered to have a more advanced level of teaching expertise (Bullough, 2005).

Knowledge of science teaching. Learning to know like a teacher means developing the knowledge of teaching used and developed within practice (Feiman-Nemser, 2008). This knowledge, unique to teaching and key to development of expertise, is called pedagogical content knowledge (Loughran, Milroy, Berry, Gunstone, & Mulhall, 2001; Shulman, 1986). In this way of thinking, PCK is an amalgamation or transformation (not an integration) of subject matter, pedagogical, and context knowledge (Gess-Newsome & Lederman, 1999). Thus, it is necessary to consider teachers’ PCK ideas directly rather than examine subject matter, pedagogical, and context knowledge to infer PCK. Moreover, pedagogical content knowledge, in contrast to practical knowledge (knowledge of classrooms and the complexities of teaching), is more formal and built on the profession’s collective wisdom (Carter, 1990; Munby, Russell, & Martin, 2001). PCK is directly linked to classroom prac-tice but is not personal or as situated in classroom events as is practical knowledge and thus may describe the ideas that enable teachers to develop the type of exper-tise that is adaptive to multiple settings. PCK is a heuristic for teacher knowledge that can be helpful in untangling the complexities of what teachers know about teaching and how it changes over broad spans of time.

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PCK is considered a knowledge of teaching that is domain specific; it is what teachers know about their subject matter and how to make it accessible to students (Carter, 1990). Definitions for PCK in science are grounded in frameworks pro-posed for teachers generally and in other domains. For science teachers, PCK includes knowledge of students’ thinking about science, science curriculum, sci-ence-specific instructional strategies, assessment of students’ science learning, and orientations to teaching science (Magnusson, Krajcik, & Borko, 1999; Park & Oliver, 2007). To develop PCK, science teachers need an understanding of science, general pedagogy, and the context (students and schools) in which they are teach-ing. It is the knowledge that enables teachers to support students’ science learning. Although the notion of specialized knowledge for teaching has been widely used, questions about the nature of PCK for teachers at different phases of their career remain (Abell, 2008). In this review, PCK in science is used as a framework to guide analysis as we look for evidence of how science teachers’ knowledge devel-ops over time.

Approach to this review. It is important to keep in mind that the notion of learning progression does not imply a specific time frame for learning specific ideas (Heritage, 2008). Thus, this review examines research for sequencing rather than what teachers know at any specific point in their careers. The fact that teachers do not step through grade levels as do students will perhaps make it a bit easier to not be distracted by what should be known at each step. In this review, learning pro-gressions for science teachers is used as a framework to examine what is reported about teachers’ knowledge of science teaching as they move through their careers. Specifically, the components of pedagogical content knowledge for science teach-ers are used as threads to trace developing teacher knowledge that otherwise may be too complex to describe clearly. Another important consideration is that the notion of learning progression does not imply that we should seek the paths to specific outcomes or goals for learning (Shavelson, 2009). In other words, succes-sively more sophisticated understanding does not mean that set goals for under-standing (e.g., standards) will be achieved. In this review, we are not attempting to find how teachers achieve a set goal of understanding. Rather, the research was examined for what ways teachers’ knowledge becomes more developed and what appears to be the sequence.

Purpose of the Review

Learning about teaching is considered a lifelong endeavor. Indeed, efforts are made to support teacher learning at different points in their careers. Teachers move from initial experiences with learners in their preservice programs to (perhaps) induction programs for new teachers to professional development programs for continuing teachers. More recently, educators have begun to think about how sci-ence teachers become teacher leaders or mentors for novices and peers (Appleton, 2008; Koballa, Bradbury, Glynn, & Deaton, 2008). There is some evidence that shifting to new roles can encourage teachers to remain in the classroom longer than otherwise might be the case (Margolis, 2008). This time frame is consistent with ideas about how expertise develops. Yet, we do not often purposefully examine teachers’ learning throughout their careers.

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The purpose of this review is to examine the research on science teachers’ PCK in order to refine our ideas about science teacher learning progressions and how to support them. The main question that guided this review was:

Research Question 1: How does science teachers’ thinking in regard to PCK progress over time with experience in the classroom?

Because much of the research on science teachers’ PCK is focused on how to improve or advance teachers’ knowledge, a second question for this review was:

Research Question 2: What variables appear to influence science teachers’ knowledge progression in regard to PCK?

In this review, we looked across the professional phases for science teachers including preservice preparation, new teachers in their first 3 years of teaching, continuing teachers working beyond the first 3 years, and teachers becoming teacher leaders or mentor teachers. Longitudinal work is difficult and thus uncom-mon. By compiling work across studies, this review composes a rare longitudinal look at the development of teacher knowledge. Although factors that appeared to influence teachers’ developing knowledge—supports or hindrances—were consid-ered, this review did not look at whether changes in teachers’ knowledge impacted their classroom practice.

Method

Pedagogical content knowledge as a construct was introduced by Shulman in 1986. Research published between 1986 and 2010 was searched for articles rele-vant to science teacher learning and pedagogical content knowledge. Multiple approaches were used to ensure a thorough search. The archives of seven journals, whose aims include the publication of research regarding teachers’ development, particularly in science education, were searched: Electronic Journal of Science Education, International Journal of Science Education, Journal of Research in Science Teaching, Journal of Science Teacher Education, Research in Science Education, Science Education, and Teaching and Teacher Education. All articles published in these journals between 1980 and 2010 were scanned to ensure articles that may not have self-identified as pedagogical content knowledge but did address at least one of the five components of pedagogical content knowledge for science teachers were included. Concurrently, educational databases were searched to identify studies published elsewhere during the same time period: ERIC, Educational Full Text, Educational Research Complete, EBSCOhost, and Academic Search Complete. Search terms included: pedagogical content knowl-edge, science teachers, teacher knowledge, knowledge base for teaching, teacher thinking, teacher professional knowledge, teacher expertise, teacher learning, mentors, mentorship, leaders, and leadership. These last four terms were used to make sure that articles regarding teacher leaders’ knowledge were not missed. In addition, the references included in the identified articles were reviewed for pos-sible relevant research articles not otherwise uncovered.

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A total of 361 articles were included in the initial database. An initial review determined that researchers used pedagogical content knowledge for multiple pur-poses, such as describing the design of professional development models, techno-logical tools, or curriculum materials; explaining student learning, teacher behavior, or teacher beliefs; guiding the development of instruments to measure pedagogical content knowledge; or exploring pedagogical content knowledge itself as a construct. Others described teacher learning or development only gener-ally (i.e., not related to science) or vaguely (e.g., state teachers learned from the session but not what they learned). After this review, 95 articles were determined to be research that described teachers’ responses or thinking in relationship to pedagogical content knowledge. A final search of international journals specifi-cally was conducted: International Journal of Science and Mathematics Education; Science Education International; Canadian Journal of Science, Mathematics, and Technology Education; and Eurasia Journal of Mathematics, Science and Technology Education. An additional 9 articles were found. After a second review of each article, 13 articles were not included because these studies did not directly describe the development of any of the five components of pedagogical content knowledge. The resulting data set used for this study includes 91 research articles.

Summaries of each article in the data set were written by closely examining the major findings regarding science teacher PCK. Teachers’ experience teaching sci-ence, grade level, number of teachers studied, and the research approach were also noted. Using NVivo qualitative research software, articles were categorized into groups by the career stage of the participants and cross-referenced with one of the five components of PCK (see Tables 1 and 2). When examining the participants, we found many of the articles did not distinguish the amount of teaching experi-ence within the participant group. If the teaching experience was mixed and the findings were not distinguished between teachers, the primary category of experi-ence was used if the range was clustered (e.g., a group of teachers with over 8 years was coded as much experience). If teachers were mentors or leaders, they were coded as leaders and were not also included in the some experience or much expe-rience category.

After this initial round of coding, each of the articles was examined for a second time, looking for specific details about the component of PCK that the article was identified as. Categories or subcodes were created for each of the five components of PCK. These categories were based on descriptions of PCK in the literature and initial coding of the articles included in this review. It was important to both rep-resent the construct and capture the nature of the research findings on science teachers’ PCK. For example, discourse was included as a category based on its importance in the literature on science classrooms while student-centered strate-gies was included as a category to represent the type of findings reported in studies of teacher knowledge. Because many researchers grounded their work in the same descriptions of PCK explored here, most categories were observed both in the lit-erature and in the findings reported. Descriptions of categories for each component of PCK are in the following:

• Orientations to teaching science includes teachers’ ideas about the purposes and goals for teaching science, the nature of science, and the nature of teaching

537

and learning science (Friedrichsen, van Driel, & Abell, 2011). For most teacher educators and researchers, an inquiry orientation to teaching, as a view of sci-ence and for student learning, is the goal for science teachers.

• Science teachers’ knowledge of students’ thinking about science includes teachers’ ideas about students’ initial science ideas and experiences (including misconceptions), the development of science ideas (including process and sequence), how students express science ideas (including demonstration of understanding, questions, responses), challenging science ideas for students, and appropriate level of science understanding (Carlsen, 1999; Grossman, Schoenfeld, & Lee, 2005).

• Teachers’ knowledge of instructional strategies in science includes teachers’ ideas about inquiry strategies (e.g., questions or exploring and including how to use, how science is developed, and how student thinking is supported), sci-ence phenomena strategies (e.g., demonstrations or predict-observe-explain

Table 1Categories of science teaching experience

Category of experience Description

Preservice science teachers Teachers in methods or student teaching experiences prior to initial certification.

New science teachers Teachers from 0 through 3 years of teaching experience. This category included experienced teachers new to teaching science and experienced science professionals new to teaching science.

Some experience teaching science Teachers with 4 to 10 years of experience teaching science. This category included studies with a predominance of teachers in this experience range. When it was not possible to determine the main experience level of the group, the study was coded for both some experience and much experience.

Much experience teaching science Teachers with 11 or more years of experience teaching science. This category included studies with a predominance of teachers in this experience range. When it was not possible to determine the main experience level of the group, the study was coded for both some experience and much experience.

Leader science teacher Teachers taking on roles as mentors for new or preservice teachers (including cooperating teachers) or leadership roles with peer teachers. Teachers with any level of experience taking leadership roles were coded as leaders and not in one of the other experience categories (i.e., some or much experience.

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and including how to use, how science is presented, how student thinking sup-ported), discourse strategies in science (e.g., argument, writing, presenting, or

Table 2Science teacher pedagogical content knowledge (PCK), aspects and categories

Components of science teacher PCK

Categories for each component of PCK

Orientations to teaching science

Teachers’ ideas about . . .•   purposes and goals for teaching science•  the nature of science•   the nature of teaching and learning science for students

Student thinking about science

Teachers’ ideas about . . .•   students’ initial science ideas and experiences

(including misconceptions)•   development of science ideas (including process and

sequence)•   how students express science ideas (including

demonstration of understanding, questions, and responses)

•  challenging science ideas for students•   appropriate level of science understanding

Instructional strategies in science

Teachers’ ideas about . . .•  inquiry strategies (e.g., questions and including how to

use, how science is developed, and how student thinking is supported)

•   science phenomena strategies (e.g., demonstrations or predict-observe-explain and including how to use, how science presented, how student thinking is supported)

•   discourse strategies in science (e.g., argument, writing, presenting, or conferencing and including how to use, how science portrayed, and how student thinking is supported)

•   general student-centered strategies for science (vs. teacher-centered) including how to use and when, how science is represented, and match to student needs and thinking

Science curriculum Teachers’ ideas about . . .•   scope of science (importance of science topics and what

science is worth knowing or teaching)•   sequence of science (organizing science content for

learning)•   curricular resources available for science•   using standards to guide planning and teaching science

Assessment of students’ science learning

Teachers’ ideas about . . .•   strategies for assessing student thinking in science•   how or when to use science assessments

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conferencing and including how to use, how science is portrayed, and how student thinking is supported), general student-centered strategies for science (vs. teacher centered) including how to use and when, how science is repre-sented, and how strategies are matched to students’ needs and thinking (Kelly, 2007; Treagust, 2007).

• Teachers’ knowledge of science curriculum includes teachers’ ideas about the scope of science (importance of topics and what science is worth knowing or teaching), the sequence of science (organizing science content for learning), curricular resources available for science, and using standards to guide plan-ning and teaching science (Grossman et al., 2005; Magnusson et al., 1999).

• Teachers’ knowledge regarding assessment of students’ science learning includes teachers’ knowledge of a variety of strategies for assessments and how or when to use assessments. Because there were fewer articles in this group, only two categories were developed (Hashweh, 2005).

Coding allowed data for each PCK category and experience level to be extracted and reviewed. Data were then examined for patterns within and then across experi-ence levels for what teachers know or think about and what appears to influence their thinking for each of the categories for the five components of PCK. Trends that were similar for teachers moving from one idea to a new idea were noted whether those teachers were early or later in their careers. Studies that made before and after comparisons or made comparisons between experience groups such as new teachers and their mentors were particularly helpful. Studies that were more limited in scope were useful in confirming trends or patterns. In addition, we looked for and described differences for grade levels (elementary vs. secondary teachers), formal or informal education (programs vs. workshops), date of the article publication, and research trends (e.g., studies during the focus on miscon-ceptions or nature of science). The final progressions presented here are based on what is described in the research examined.

Findings

The final data set represented each component of PCK across the experience levels (see Table 3). Of the articles examined for this review, only five were longitudinal studies following teachers for 2 or more years. In addition, many studies focused on experienced teachers did not distinguish years of experience beyond stating the overall range of experience (e.g., stating teachers had 4 to 25 years of experience) for all teachers participating in the study or professional development. This is interesting since the development of PCK is thought to progress over time as teach-ers gain additional years of experience in the classroom. Yet, all teachers were given the same level of professional development as if their knowledge of teaching were similar after an initial induction period. In contrast, preservice teachers’ ideas were frequently described at multiple points along the academic year leading to certification. There were many studies that described teachers’ ideas before and after a methods course or student teaching, or occasionally both. In a few cases, experienced teachers new to science were the focus of research. Because the focus of this review was on subject-specific teaching knowledge (i.e., science PCK), teachers in these cases were coded as new teachers. Research on preservice

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teachers was abundant while research on leader teachers was scarce. Similarly, research on orientations and student ideas was more frequent and research on what teachers think about science phenomena or assessment was uncommon.

Orientation to Teaching Science

Many studies included in this section focused on nature of science specifically as a research agenda. Researchers were not necessarily focused on teachers’ peda-gogical content knowledge, but these studies did tend to explore teachers’ ideas about what to teach in science and how to approach science instruction. Other studies included in this section described teachers’ ideas about teaching science as a component of describing how teachers approached teaching during specific events such as student teaching or working with a new curriculum.

Table 3Number of published papers for each level of teacher experience and category of pedagogical content knowledge (PCK)

n = 91

Preservice (n = 50)

0 to 3 years (n = 23)

4 to 10 years (n = 19)

>10 years (n = 26)

Leaders (n = 7)

Orientations (n = 48) 25 10 11 12 4 Purposes/goals 16 3 5 6 3 Nature of science 11 6 9 7 2 Nature teach/learn 22 8 5 4 2Student ideas (n = 51) 28 11 12 15 5 Initial ideas 19 9 8 10 4 Development of ideas 14 10 10 10 3 Expression of ideas 7 2 1 2 2 Challenging ideas 12 3 5 7 0 Appropriate

understanding7 0 0 0 1

Strategies (n = 39) 18 13 12 13 2 Inquiry 6 6 3 5 1 Phenomena 14 6 7 7 1 Discourse 7 3 5 5 0 Student centered 12 7 6 4 1Curriculum (n = 28) 14 6 7 11 2 Scope 11 3 5 7 2 Sequence 2 1 2 3 1 Curricular resources 8 4 3 3 2 Standards 1 2 2 4 0Assessment (n = 20) 8 3 4 10 1 Strategies 7 3 4 10 0 How/when to use 8 3 3 8 1

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Purposes and goals for teaching science. Researchers were not consistent with their use of the terms purpose and goals and frequently used goals to identify a range of objectives. Findings were examined for descriptions of teachers’ ideas about why science is taught and what was important about teaching science. Two progressions were identified, one for the purpose and a second for the goals for teaching science.

The overarching purpose of teaching science was described by teachers as pre-paring students: first by gaining students’ attention, then developing students’ skills, followed by supporting understanding, and finally focusing both on value and understanding. Secondary and elementary teachers tended to differ somewhat in their ideas about why it was important to teach science. As preservice teachers, both groups thought it was important to prepare students for the next level of schooling or life. However, elementary teachers were interested in developing stu-dents’ curiosity and providing them with fun ways to remember information while secondary teachers focused on building confidence and developing an appreciation for the usefulness of science. This difference is illustrated by a set of companion studies that looked at teachers’ concepts of teaching across the preservice year (Lemberger, Hewson, & Park, 1998; Meyer, Tabachnick, Hewson, Lemberger, & Hyun-Ju, 1999). In four interviews across the methods and student teaching semes-ters, 15 secondary and 20 elementary teachers, respectively, were asked how they felt about their lessons, what they did during their lessons, and reasons for their actions. Reported in case studies, one elementary teacher began with the idea that “the primary role of the science teacher was the need to find ways to make the information interesting to the students so that they would have an easier time remembering it” and later described that “science instruction is helping the stu-dents to discover this known body of information” (Meyer et al., 1999, pp. 327–328). In contrast, one secondary teacher described science teaching as “somehow getting the students to think about the topic” and “came to class dressed as an atom.” She later stated that “learning occurred when students built their own mean-ings” and that science teaching is “causing them to come up with those things themselves” (Lemberger et al., 1998, pp. 351–352). In studies focused on teachers with more experience, some teachers still described the purpose as gaining atten-tion, but other teachers were concerned that students build understanding that would enable them to continue to study science. The interplay of preparing stu-dents to explain everyday phenomena and to study science was more evident for experienced and leader teachers. The nuance of elementary versus secondary was still evident but not as dramatic.

Progression for purpose. The purpose of teaching science is to prepare stu-dents for the next level of schooling or life by encouraging curiosity and providing fun ways to remember information (elementary) or by building student confidence and developing students’ appreciation for the usefulness of science (secondary) → The purpose of teaching science is to prepare stu-dents by teaching them how to find information (elementary) or develop understanding (secondary) by themselves → The purpose of teaching science is to prepare students by supporting conceptual learning to enable further study in science → The purpose of teaching science is to help students scien-tifically understand phenomena in everyday life by making content relevant

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and available to children (elementary) or by modeling content and thinking (secondary)

The primary goal for teaching science was to address science information and concepts. Preservice teachers were clearly focused on covering basic content cor-rectly and completely; they thought teachers should cover the material by present-ing facts and correct explanations. As new teachers gained experience with students, their goals included the avoidance of repeating what students already knew or to correct misconceptions (Kang, 2007). This view of the goals for sci-ence—to correctly cover basic content—was reported for some teachers in every category of experience. Across the levels of experience, teachers did not typically include a range of science knowledge types in their goals for teaching science. For example, teachers tended to not include argumentation or the nature of science as goals. This was true even when teachers considered science itself as a knowledge field to be setting the goals for what should be taught. Teachers however, did add inquiry science skills or what they sometimes called thinking skills to the list of goals. It is important to note that goals for process skills often meant that teachers would add process ideas to the content they would correctly explain. This is illus-trated in a study to examine the relationship between personal epistemologies and science teaching goals. In this study, 23 secondary methods students described their ideas about teaching science in structured essays and reflections (Kang, 2008). Although the majority (17 out of 23) of the teachers described knowing as receiving knowledge, about half of the 17 (8 vs. 9) included inquiry process and/or thinking as a goal. These teachers described inquiry process as knowledge they “received during the lecture” (Kang, 2008, p. 486). Of the 6 teachers who described knowing as seeking one’s own answers, 5 included inquiry process and/or thinking as a goal. These 5 described thinking skills as “critical and analytical thinking skills, to understand inner workings of science” (Kang, 2008, p. 488). The goals described by researchers were sometimes dependent on the purpose of the research. If learning to teach the nature of science was the context of the study, then some teachers were reported to begin to think about nature of science as a possible goal for science teaching. If the researchers were interested in what ideas teachers had about inclusion, then the goal of including all students was described. Researchers also reported that teachers had multiple, non–science content goals for teaching science such as maintaining a safe environment or helping students develop social skills (Abd-El-Khalick, Bell, & Lederman, 1998). These “goals” were not included as PCK for science.

Progression for goals. The goals for teaching science include information and concepts, are identified by the curriculum, and should be presented cor-rectly and completely → The goals for teaching science include information and concepts but may include some science processes, are identified by the curriculum, and students should understand concepts → The goals for teach-ing science include information, concepts, processes, and possibly some aspects of the nature of science; are determined by science as a body of knowledge; and students should develop thinking skills and link ideas → The goals for teaching science include information, concepts, processes, and pos-sibly some aspects of the nature of science; are determined by science as a body of knowledge and phenomena in everyday life; and students should benefit from understanding the ideas

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Teachers’ ideas about the purposes and goals for teaching science appeared to be influenced by the agenda of the educational experience, more so for process goals than nature of science goals. Programs that focused on helping teachers understand and use inquiry often reported that teachers added science process or inquiry skills as a goal for student learning. Programs focused on the nature of science, on the other hand, reported limited success in adding nature of science as a content goal. The progression of purposes and goals described also seems to be influenced by time working with students and developing an interest in adding science to students’ futures. Finally, content knowledge was often shown to have a relationship to specific topic goals and ideas about purposes and goals generally. Content knowledge was reported to be primarily based on college science courses that tended to be traditional lecture-based instruction.

The nature of science. Many teachers, preservice teachers in particular, had a view of science as discrete with few connections or themes. This view is not surprising since most teachers’ experiences with science are probably in college courses where science is often presented as discrete ideas. Teachers also confused science procedures with the nature of science. With increasing levels of experience, teach-ers tended to include more features in their ideas about science such as the obser-vational nature of data or creativity. Experienced teachers were mixed in their view of science, with some having a linear and topical view similar to textbooks while others had a more integrated view of science (Abd-El-Khalick, 2006). The features of teachers’ ideas about the nature of science were well described in a study focused on six cooperating physics teachers from three teacher training schools in Finland (Asikainen & Hirvonen, 2010). These teachers had many years of experi-ence guiding preservice teachers. In a 30- to 60-minute interview, teachers were asked to describe the knowledge base of a skillful physics teacher. One teacher described physics as structured and hierarchical, an experimental science, and hav-ing theories that are constantly developing. Another teacher stated that some areas of physics are not questionable and the philosophy of science is limited to modern physics. A third teacher described physics as the relationship between theories and observations. The authors interpret this range as each teacher having a unique view of the philosophy of science (i.e., nature of science).

Progression. Science is a set of known ideas that can be divided into small pieces of information to be delivered to the learner and knowledge is divided into right answers and misconceptions → Science has some empirical and tentative aspects and includes specific ideas such as the nature of data or creativity but process and nature of science are confused and misunderstood by teachers → Science is an integrated field of knowledge with connections and themes that might be hierarchical or web like and includes big ideas such as patterns, systems, models, or relationships

Overall, little progress in understanding the nature of science was reported. As might be expected, experiences in college science courses influenced teachers’ initial ideas about the nature of science. Instruction for teachers, often in preservice courses, was the primary initiator of teachers including the nature of science as a learning goal. To make progress, it appears that ongoing instruction is helpful. For example, in the third year of a classroom-based professional development addressing science

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and literacy for English language learners, elementary teachers were reported to make connections between concepts and emphasized big ideas (Lee, 2004). In another example, an experienced elementary teacher made progress in her ideas about the nature of science throughout a yearlong experience of four graduate courses that included two courses that emphasized the nature of science (Akerson & Abd-El-Khalick, 2003). These reports support the idea that instruction is helpful but takes time and effort. The fact that teachers tended to not have additional instruction in science specifically may explain the uneven and limited progress in this category.

The nature of learning science for students. The initial view of learning for many teachers was that learning was a process of receiving correct information. These teachers described a need for lectures, note taking, and presentation of material. Teachers also described the need for students to discover information on their own through reading or hands-on activities. At first this might seem contradictory, but in an in-depth case study of an elementary teacher, Bryan (2003) interprets this as two facets of a transmission model of learning. In one situation students are receiv-ing information from the teacher and in the other situation they are receiving infor-mation from the activity. As long as the teacher does not give the answer, it is seen as the students discovering it from the activity (Bryan, 2003; So & Watkins, 2005). A related idea reported by researchers focused on teachers’ ideas about the nature of science is that students will learn the nature of science by doing science. This was in part confounded by the fact that teachers confused process and nature of science (see previous discussion). The transmission view may also lead teachers to control information and activities such as the procedures of investigations (Bryan, 2003). Preservice teachers, in particular, also believed that most students would learn in the same ways that they themselves learned science when they were stu-dents, which was often through listening rather than doing science.

Many researchers were interested specifically in what teachers thought about inquiry or problem-based science. Findings reported describe teachers who try doing inquiry but do not believe it is the best way for students to learn or who worry about losing control of the flow of information (Briscoe & Peters, 1997; Crawford, 2007). Other researchers were focused on helping teachers understand conceptual change or constructivist theories of learning. In many cases, these teachers would say students need to discover ideas for themselves as described previously. Others, however, began to think about students building on their ideas (rather than adding to) and helping students understand these ideas. Based on con-structivist ideas, some projects focused on problem-based learning. In a study of three experienced secondary teachers working to develop a new curriculum, some shift was seen in teachers’ ideas about learning (Coenders, Terlouw, Dijkstra, & Pieters, 2010). Initially, teachers struggled with the idea of a problem covering the material but at the end of the year stated that learning could begin with a context. They also stated, as did teachers in other studies, that “new” approaches were add-ons to traditional practice. More advanced thinking about learning was seen in a study of elementary leader teachers. One teacher described her ideas about learn-ing as that when she gave her students the freedom to explore an area or concept it allowed them to “learn more and find their feet with concepts that are probably further than what we expected. . . . It allowed them to explore things with a greater depth” (Appleton, 2008, p. 534).

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Progression. Students learn science by receiving and remembering informa-tion through listening (lectures or directions), reading (textbooks), or doing activities (discovering on their own known); students learn science the same way they themselves (teachers when they were students) learned (often by listening); and students learn the nature of science, in particular, by doing science processes → Students learn science by building on their ideas or by actively developing new concepts, but new approaches (e.g., those that require creativity and decision making) are add-ons to traditional practice → Students learn science through exploring ideas or contexts (possibly prob-lems) with guidance from teachers

Teachers’ ideas about learning seem to be influenced by a combination of instruction and experiences with students. Preservice teachers were likely to describe learner-centered ideas based on their methods courses but struggle with these ideas in their first year of teaching. Experienced teachers were as likely to have transmission views of teaching as early teachers except when they partici-pated in professional development such as curriculum reform or working with preservice education. There is, perhaps, a slight bias in the reports favoring ele-mentary teachers in shifting toward constructivist views of learning. Mentoring a novice teacher, albeit a small sample of studies, seems to be helpful.

Students’ Thinking About Science

Many studies in this category were focused on teachers’ ideas about student misconceptions. These studies contributed mainly to the initial ideas and develop-ment of ideas categories. In spite of the many studies on misconceptions and con-ceptual change, few actually addressed for teachers the issue of ideas that are challenging for students. Very little was reported regarding teachers’ thinking about appropriate levels of understanding. This may be related to the fact that standards are often presented as the goal level of understanding for students.

Students’ initial science ideas and experiences. Multiple studies reported that teachers were not aware that students had ideas other than what they were taught in school. This may be, in part, because some of these studies were dated prior to the emphasis on student misconceptions. However, this finding was also reported by more current studies and for experienced teachers. For example, in a recent study of 30 elementary teachers representing 12 schools in seven different districts across the state of California with teaching experience of 1 to 35 years, several teachers suggested that students do not have personal ideas about science with statements such as: “Children don’t have much of an idea about science in any way. I assume they are blank slates, ready to take in whatever I have to give” and “[Students] don’t have ideas about science. You can’t have wrong ideas about sci-ence if you don’t have any ideas at all. . . . They just don’t think about science” (Gomez-Zwiep, 2008, p. 442). And in spite of having heard about the idea of misconceptions, one third of these teachers were unable to give even one example of a student misconception from their own experiences, even after examples were provided. This finding is consistent with teachers’ ideas that science is a set of known ideas and students learn science by receiving correct information.

When teachers do become aware that students have ideas, some assume these are the ideas that will need correcting while others think of these ideas as a place

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to start instruction so as to not bore student with ideas they already know. (Researchers themselves also seem to have moved through this phase as they framed their work with misconceptions then alternative, naïve, and later prior con-ceptions.) For some teachers, learning about their students’ ideas and that these ideas were not accurate prompted them to revisit their own ideas. Some teachers were interested in learning what students found interesting so they could gain students’ attention at the beginning of a lesson. To uncover students’ ideas, most teachers listened to their students, initially only at the beginning of a topic, and more experienced teachers read what their students wrote on assessments. Although not common, a few teachers did mention reading professional resources about students’ ideas (Hubber, Tytler, & Haslam, 2010). Linking students’ ideas to instruction was a more advanced notion. Otero and Nathan (2008) examined the ideas of 61 elementary preservice teachers and found a range of thinking regarding students’ prior knowledge. They found teachers who did not respond, who responded only to academic ideas, and who responded to experience-based and academic ideas but did not link the two. Teachers who thought of experience-based and academic ideas as integrated were considered the most responsive. From the beginning to the end of a 15-week semester, some shift across these phases was reported for the group.

Progression. Students do not have initial ideas or experiences relevant to sci-ence except for ideas from school (correct ideas) → Students do have initial ideas or experiences relevant to science, but these are misconceptions (wrong ideas) or simply unknown to the teacher → Students have initial ideas or experiences relevant to science and it is important for teachers to know (some teachers can give examples) or uncover these ideas as a place to start or cor-rect, and students’ initial ideas may prompt teachers to reevaluate their own (teachers’) ideas → Students have initial ideas or experiences relevant to science and it is important for teachers to look for these by listening to stu-dents, reading students’ work, or reading the literature on students’ ideas (rarely) → Students think and develop their own ideas from multiple experi-ences in and out of school and these ideas are the basis of learning

In general, reports describe elementary teachers as tending to be more unaware of student ideas than teachers in high school are. Perhaps the more concentrated focus on content brought teachers’ attention to student science ideas specifically. When findings across studies were examined, hints of regression were seen, spe-cifically when instruction for teachers was absent. Formal instruction for teachers seemed to positively influence teachers’ progress. Preservice teachers in prepara-tion programs and teachers in master’s programs made progress in their thinking about students’ science ideas. On the other hand, teachers with a lot of classroom experience alone did not show the same progress and, perhaps, regressed, suggest-ing the possibility of two different trajectories.

Development of science ideas. Consistent with the aforementioned descriptions, teachers tended to begin with a simple view of student idea development. Teachers stated the importance of being correct, clear, and concrete. Preservice or new teachers did not necessarily consider the impact of their instruction on students’ science ideas (Akerson, 2005). In some cases, the very structured nature of preser-vice experiences allowed teachers to report that they thought it was important to

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give students opportunities to express ideas or participate in science activities. For example, when assignments were explicitly focused on analyzing materials for questions that make thinking visible, preservice teachers were able to be critical of lessons regarding this feature (Beyer & Davis, 2009). Another approach to focus teachers on their students’ idea development was to give teachers instruction on conceptual change. In one study, teachers participated in an action research project as part of a graduate course covering conceptual change pedagogy. At the end of the course, most teachers described the importance of probing and utilizing stu-dents’ preconceptions in science teaching but demonstrated various levels of understanding of student learning. Only 4 out of 14 teachers talked about assisting students’ knowledge construction or guiding students’ ideas to scientific thinking (Kang, 2007, p. 479). Thinking about students developing ideas appears to take time and reflection. In a study that followed one elementary teacher through pre-service to new to established teacher, it was reported in Year 9 that she chose les-sons to develop students’ ideas (Mulholland & Wallace, 2005).

For development of science ideas, the possibility of two trajectories was even more apparent than for initial ideas. When teachers benefited from instruction, they made progress toward understanding how students develop ideas. In contrast, teachers with experience only seem to become more focused on how to present ideas in ways that require less complex thinking on the part of students. Some teachers described the need to break content in small pieces of information and interpreted challenging ideas, such as the cell, as being boring (Cohen & Yarden, 2009; Lemberger et al., 1998). One path emphasizes students’ ideas and the other emphasizes students’ work.

Progression. Students’ science ideas increase when teachers give them cor-rect ideas → Students’ science ideas develop when teachers simplify complex ideas and make abstract ideas concrete and correct wrong ideas → Students’ science ideas develop when teachers use multiple ways to present an idea for different students and learning styles (variety) → Students’ science ideas develop when they have multiple opportunities or representations to experi-ence science and time to express their science ideas → Students’ science ideas develop when teachers are responsive to their ideas and reasoning by adjusting instruction (sequence and integration)

Alternative path. Students’ science ideas increase when teachers give them correct ideas → Students’ science ideas increase when teachers simplify complex ideas and make ideas concrete → Students’ science ideas increase when they work hard → Students’ science ideas increase when ideas are presented in very small chunks and when excitement is added to boring topics

Work within a formal program, either preservice or master’s level, was clearly associated with positive progress in thinking about how to develop student ideas. Preservice programs launched teachers in a positive direction and graduate study or curriculum work in conjunction with classrooms appeared to help teachers think about students’ ideas. For example, in the curriculum reform work mentioned pre-viously (Coenders et al., 2010), teachers learned that students did not have a good understanding of models and saw the need for teachers to guide students when they did not link concepts on their own. Students’ questions and listening to students’ explanations appeared to be helpful for teachers. Experiences with students, in and

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of themselves, however, seemed to lead teachers to simplify ideas and focus on students’ enjoyment.

How students express science ideas. Simple views of how students express ideas are also consistent with teachers’ early ideas about science and learning. The view is that students state their ideas in response to teachers’ questions. Preservice and new teachers explained that students give funny answers because the teacher’s question was not worded well or students’ understanding was not correct (Akerson, 2005). Thus, they concluded that they, as teachers, should be very strict in their use of language. For some teachers, experiences with students lead them to notice students’ ideas and then probe students for explanations in order to listen to stu-dents’ thinking (Avraamidou & Zembal-Saul, 2005; Zembal-Saul, Krajcik, & Blumenfeld, 2002). Experienced teachers were able to use a variety of approaches such as observational notes and assessments to learn what students were thinking. Early teachers might watch their students for clues but did not mention assess-ments as revealing student ideas. Leader teachers recognized that kid language was different from adult language and guided their interns to notice how students’ behavior and questions revealed their thoughts (Akerson, 2005; Nilsson & van Driel, 2010). Whereas early teachers listened to what students had to say, experi-enced teachers were more likely to hear or interpret what students meant. Leader teachers were able to build from student views to give appropriate tasks such as readings that would guide students.

Progression. Students express their science ideas in response to teacher ques-tions; if students give unexpected answers then teachers need to reconsider how they state their questions → Students express their science ideas in the questions they ask and when teachers probe students for explanations (teach-ers listen to students) → Students express their science ideas in the questions they ask, when teachers probe students for explanations, and in what they write for assessments → Students express their science ideas in kid language and behavior that reveals their thoughts (hear/interpret students) → Students express their science ideas in ways that reveal their thoughts and teachers should respond accordingly

Experiences with students, listening and thinking about their learning, seemed to be the main influence on teachers’ ideas about how students express ideas. Although preservice instruction was shown to enable teachers to include questions in lesson plans that should give students opportunities to describe their ideas, whether these teachers understood students’ expression of ideas cannot be assumed. Experienced teachers studying their students’ work did learn about assessments as a source of learning what students are thinking (Coenders et al., 2010). Leader teachers demonstrated more sophisticated thinking about students’ versus adult language and how students express their ideas. Preservice teachers learned about their students’ expression from these mentors.

Challenging science ideas. Most preservice teachers did not think about reasons students might find ideas difficult and thought about science ideas as right or wrong. Preservice middle grades and elementary teachers did not think students would have difficulties while preservice secondary teachers believed students

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would have the same difficulties they themselves did as students (Kapyla, Heikkinen, & Asunta, 2009). After experiences with students, some teachers explained student difficulties as being due to vocabulary, intangible topics, and visualization problems and were unaware of documented challenges for students regarding specific science ideas (Cohen & Yarden, 2009). Some teachers explained that students were challenged because they did not have enough background knowledge. In a study with three experienced middle grades teachers learning how to use representations to help students understand forces, teachers’ explanation of student difficulty as being a lack of background knowledge is linked to teachers’ notion of science and learning:

You come into class with some certain concepts that you want to deliver and you end up with a lesson that is totally different to what you planned, because it is usually directed by the students. The questions they ask are challenging they ask questions I can’t answer to a level or a point that the kids can under-stand [as] they don’t have that background knowledge so we try and simplify for them and it is not easy. (Hubber et al., 2010, p. 19)

In other reports, some more experienced teachers explained student difficulties by identifying topics as boring, for students and themselves. In this case, there is a connection with the alternative pathway described previously for the development of student ideas. On the other hand, some experienced teachers were reported to have more developed understandings of the challenges students face that were specific to science such as substantiating claims or scientific models. While these teachers mentioned reflection on student difficulties as a reason for changing how they taught a topic, they were vague about what to do (Drenchsler & Van Driel, 2008).

Progression. Science ideas will not be challenging for students (elementary) or challenges will be the same challenges teachers themselves had as students (secondary) → Science ideas are challenging in general ways such as vocab-ulary or abstractness → Science ideas that are challenging are specific to science areas such as genetics (linking genes with traits) and processes such as substantiating claims or scientific modeling

Alternative path. Science ideas will not be challenging for students (elemen-tary) or challenges will be the same challenges teachers themselves had as students (secondary) → Science ideas will challenge students when they don’t have enough background knowledge to understand → Science ideas will challenge students when topics are boring

Teachers’ thinking about challenging ideas was shown to be influenced by their own understanding of specific science ideas for both novice and experience teach-ers (Cohen & Yarden, 2009; Kapyla et al., 2009). Teachers seem to be more likely to understand the nature of challenges for specific ideas that they had spent more time exploring themselves. Teachers’ views of science and learning also appear to influence teachers’ ideas about challenges for students.

Appropriate level of science understanding. There were a few studies for preser-vice teachers and only one for leader teachers with no reports in between. Thus, it was not possible to suggest a learning progression in this category.

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Instructional Strategies in Science

Often reports in this area consisted of lists of what strategies were used by teachers but did not always describe how or why teachers were thinking about strategies. The goal often appeared to be to encourage teachers to try strategies with less discussion of whether teachers learned or why they used a strategy. Teachers’ ideas were often implied by their actions. Many of the reports were focused on general student-centered strategies rather than strategies more specific to science. Discourse in science was generally not explicitly addressed. Most of the studies for experienced teachers did not separate years of experience and grouped these teachers together.

Inquiry strategies. Teachers had a range of ideas about inquiry strategies but most reports describe teachers having ideas that were progressing toward student inves-tigations. In science education there has been considerable effort to help teachers understand and use inquiry strategies, particularly in preservice education. Thus, many reports regarding inquiry described preservice and new teachers who had ideas about inquiry that included questions and evidence. There were, however, reports of teachers who struggled with the idea of inquiry. These teachers included hands-on activities or opportunities to “discover” concepts as being inquiry approaches. A study of five preservice secondary teachers and their mentors illus-trated a range of inquiry ideas from uninformed to informed for the preservice teachers and from traditional/closed to inquiry/open for their mentors (Crawford, 2007). While most teachers were midrange, there were preservice and mentor teachers at each end of the range. For several of the preservice teachers, inquiry was a conflict between ideas about learning and meeting expectations in the class-room. For example, one teacher stated it was best when students have their own questions but she was worried about addressing standards. Some of the preservice teachers developed the idea that inquiry was not appropriate for high school stu-dents. For the most inquiry-based intern, inquiry included students asking ques-tions, working with data, and developing explanations. Another intern more midrange modified traditional labs while the intern least inquiry based described hands-on activities as inquiry. Across the reports, when teachers begin to think about inquiry they focus on data collection. Some teachers used demonstrations or teacher-led activities for students to observe and record data. The first step toward inquiry strategies appears to be for teachers to remain somewhat teacher centered but to include opportunities for students to collect evidence. Teachers new to inquiry and preparing for National Board Certification increased the opportunities for inquiry by adding inquiry lessons and converting traditional lessons to inquiry (Park & Oliver, 2008). These reports suggest that specific features of inquiry are easier to learn, such as data collection, and other features require teachers to do more rethinking (with educational support), such as having students pose ques-tions (Weinburgh, Smith, & Clark, 2008).

Progression. Inquiry strategies are activities that are hands on or that lead to “discovery,” are difficult to enact, and may be inappropriate for students → Inquiry strategies are primarily opportunities to collect data through observa-tions or experimentation and can be teacher centered → Inquiry strategies are opportunities for student to pose questions or collect and work with their own

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data, and traditional lessons can be converted to inquiry lessons → Inquiry strategies include students posing questions, designing investigations, col-lecting evidence, and making claims (with instruction)

Teachers preparing for National Board Certification increased their number of inquiry lessons (Park & Oliver, 2008). One study reports that a new teacher who had taken standard science courses in her preservice program focused on investiga-tions, working with data to answer questions, hands-on activities, and group dis-cussions while another new teacher who had taken science courses designed for education majors focused on students designing investigations, posing questions, interpreting data to form evidence, and constructing and communicating evidence-based claims (Avraamidou & Zembal-Saul, 2010). This effect was also seen with yearlong individual instruction for the teacher in the classroom (Weinburgh et al., 2008). These reports highlight the impact of science content courses and class-room-based teacher education on how teachers think about inquiry strategies for their students.

Science phenomena strategies. There were few reports that focused explicitly on teachers’ thinking about strategies to engage students with science phenomena. This is interesting since science as a field is based on understanding natural phe-nomena. Reports described teachers stating the value of a variety of representa-tions such as students participating in hands-on activities; reading about science; viewing scientific videos, pictures, or physical models; or hearing descriptions of real-world applications. Elementary teachers used trade books to relate and help explain phenomena to children (Akerson, 2005). Demonstrations were seen as a way to have students gather data without doing an investigation themselves or to save time (Avraamidou & Zembal-Saul, 2005; Crawford, 2007). Research that did examine teachers’ ideas about phenomena strategies more closely studied second-ary teachers, were focused on specific science areas such as forces or chemical equilibrium, and made links to challenging science ideas. These studies usually examined teachers’ understanding of the science represented. In a comparison study of novice and expert chemistry teachers, where novice and expert were defined by years of teaching experience, experienced teachers were reported as knowing more demonstrations, knowing more about the complexity of the demon-strations, and having better quality explanations (Clermont, Borko, & Krajcik, 1994). In conjunction with ideas reported for challenging ideas, it appears that teachers begin to think about what difficulties students might have with a science idea. But how this was related to phenomena strategies was not explored. It appears that teachers begin by thinking about multiple representations of science phenom-ena that can be viewed by students. And, perhaps teachers progress to knowing more about more ways to represent phenomena and to thinking about what diffi-culties students might have with a science idea. But teachers’ ideas about engaging students with phenomena, linking challenging science ideas with the phenomena, and guiding them to develop scientific explanations were generally not described. Thus, a progression for thinking about phenomena strategies was not uncovered.

Discourse strategies in science. The use of language within science was generally not a central theme and was not reported as a separate category. Teachers’ ideas

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about spoken discourse were reported in descriptions of what teachers thought about discussions and explanations. Teachers’ ideas about written discourse were reported in descriptions of what teachers thought about reading and writing assign-ments. It is important to point out that the term discussion was used by most teach-ers but it was not always clear what teachers understood a discussion to be. In some cases, it appeared that teachers understood discussion to be any conversation or talk with students. Other descriptions such as having students share explanation or evidence claims are more likely to be interactive discussions. Some beginning teachers frequently saw science only in conversations that involved the teacher and did not consider that students might be able to explain concepts to one another. Frequently, writing, talking, or group work was seen as a way to see what students were thinking, launch a lesson, and, in some cases, support teacher-centered approaches such as determining where to begin a lecture and motivating students to listen (see previous section on student thinking). Overall, discourse was not usually viewed as a goal for science in and of itself. Thus, the progression in this category is somewhat undeveloped and tentative.

Progression. Language use in science is having conversations with the teacher and student–student talk is not considered → Language use in science includes class “discussion,” reading textbooks and other books for research, and writing reports or summaries → Language use in science includes discus-sion (possibly in groups) or writing (e.g., journals) for students to describe their ideas and explain their thoughts about scientific concepts → Language use in science includes students communicating claims from investigations as an argument (with science course for teachers)

Explicit focus on language use in science was associated with teachers using and then seeing the value of students’ writing and conversations. For example, teachers preparing for National Board Certification began to include journaling as a form of student–teacher discussion (Park & Oliver, 2008). In other work focused on science for English language learners, literacy was a joint theme with science (Lee, 2004). These teachers first thought about vocabulary and later learned the importance of probing students’ ideas and encouraging students to elaborate, explain, or justify responses. Teachers’ confidence in their content knowledge influenced how they had students participate in classroom conversations. Teachers with a weaker content understanding spent more time listening to students, used group work, and put students in the role of the teacher (Akerson, 2005; Friedrichsen et al., 2009). Teachers who took a science course designed for education majors engaged students in constructing and communicating claims resulting from inquiry-based investigations in the form of an argument (Avraamidou & Zembal-Saul, 2010).

Student-centered strategies for science. Findings in this category were confounded with inquiry strategies described previously. This makes sense in that inquiry is a strategy in science intended to be student centered. Activities that might appear to be student centered were sometimes used by teachers to compensate for their own uncertainty with the content (Carlsen, 1991). For example, group work was some-times used by new teachers when they themselves did not understand a science topic. Preservice teachers were often focused on management and, thus, on

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teacher-centered activities. Some teachers had more initial success with strategies intended for individual students such as giving students feedback on journal entries. In a 10-year study of one elementary teacher, how her ideas about student-centered science develop is described (Mulholland & Wallace, 2005). As a begin-ning teacher she struggled with group work and realized she needed to spend more time teaching group skills but worried about completing the unit on time. As an established teacher she said that “she deliberately planned a short quiet period immediately before a hands-on science lesson. They get excited by science. So you need to settle them down. And then bring them to [the space where they will do science]” (Mulholland & Wallace, 2005, p. 780).

Progression. Student-centered strategies are hands-on and small group activ-ities; teachers consider activities known to work, management, and their own (teachers’) lack of knowledge to select strategies → Student-centered strate-gies are whole class idea collection such as KWL charts (what we know, what we want to know, and what we learned) and individual opportunities to share ideas such as journals or teacher feedback → Student-centered strategies are individual and student-student opportunities to develop and share ideas such as generating questions and communicating claims and explanations

Successful experiences in the classroom encouraged teachers to include new strategies (Coenders et al., 2010; Mulholland & Wallace, 2005). Teachers were influenced by their own confidence with science, management, and student-cen-tered strategies. Instruction for teachers, mostly seen in the form of professional development sessions, appears to encourage teachers to try specific strategies. Similarly, the National Board Certification process expanded teachers’ knowledge of instructional strategies.

Science Curriculum

The aspects of science curriculum tended to be areas that teachers were initially unfamiliar. Teachers did not know what science ideas to include in their instruction or what resources were available. As teachers gained experience, they knew more about science curriculum. There was not a clear progression, but rather, teachers became familiar with curricular aspects such as what resources were available and what were the specific science standards.

Scope, sequence, standards, and resources. Separate trends for each category of science curriculum were not obvious. What was found was a cluster of character-istics for beginning and a different cluster of characteristic for more experienced teachers.

Progression. Teachers are uncertain about what topics are appropriate and allow the materials to define the scope, think about sequence only generally, are unfamiliar with science standards, and are unfamiliar with available resources and rely heavily on curriculum materials → Teachers integrate sci-ence concepts and other subjects, are flexible in their thinking about sequenc-ing, are familiar with and use standards, are unfamiliar with available resources, and rely heavily on curriculum material for scope and sequence

Activities that involved teachers in exploring curriculum added to their knowl-edge in this area. For example, participation in the revision of the school curriculum

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resulted in teachers knowing much more about science standards (Friedrichsen et al., 2009). Likewise, preparing for National Board Certification led teachers to think more about the scope and sequence of science for instruction (Park & Oliver, 2008).

Assessing Science Learning

Assessment as a component of pedagogical content knowledge has not been a clear research objective. In addition, much of what is described about teachers’ ideas was implied by what researchers found as to what teachers do or do not do regarding assessment. There were few studies that addressed teachers’ ideas about assessing students’ science learning and only one was found for leader teachers. On the other hand, experienced teachers were the focus of several studies examin-ing assessment knowledge specifically. This was the only category where experi-enced teachers were represented in more studies than early teachers.

Strategies for assessing student thinking in science. Reports indicated that during early phases, teachers tend to not think much about assessment. Preservice and new teachers did not typically include assessments in their plans, but new teachers did plan to use informal questions to find out what students know throughout a unit while preservice teachers planned to grade student worksheets (Friedrichsen et al., 2009). Teachers continue to learn new assessment strategies such as portfolios, performances, presentations, and journals, often as part of a project such as the National Board Certification process, curriculum revision work, or because of dis-satisfaction with published tests (Goodnough & Hung, 2009; Kamen, 1996; Park & Oliver, 2008). More experienced teachers, particularly if they participated in graduate work, were more likely to rethink science assessments. Experienced teachers in a yearlong program to study assessment design for their curriculum units that included instruction for interpreting their students’ work made important progress in understanding assessment design and in understanding the relationship between the science and the assessment tasks (Gearhart & Osmundson, 2009). There were no studies on leader teachers and what they know about assessment strategies specifically.

Progression. Assessments are traditional formats such as test at the end of a unit and assessments in science are the same as other subjects → Assessments include informal questioning to know what students are thinking → Assessments include a variety of strategies such as journal entries, portfolios, presentations (when taught and practiced) → Assessments require planning such as developing criteria and should be matched with specific science ideas

Working with students was not only very helpful, it appeared to be necessary for teachers to think about strategies for assessing science learning. For example, preservice teachers needed to experiment with performance assessment in their field experiences, and learning to interpret students’ work was key to learning how to develop improved questions for experienced teachers (Gearhart, Nagashima, & Pfotenhauer, 2006; Morrison, McDuffie, & Akerson, 2005). Instruction for teach-ers on the types and uses of assessment also seemed necessary to expand teachers’ ideas. Teachers began with traditional assessments such as tests. This was likely related to what they experienced in their own schooling. Careful thinking about

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science assessment appears to have been an area underrepresented in educational programs for science teachers.

How or when to use science assessments. Preservice teachers, and sometimes experienced teachers, reported thinking of assessment as an end of unit event with the goal of assignment of grades for students (Sanchez & Valcarcel, 1998; Wang, Kao, & Lin, 2010). When asked about assessment during a unit, preservice and new teachers stated that the purpose of assessment was to see if or what material needed repeating. New teachers also approached assessment in this way, but in addition they began to wonder about alternative assessments when students were not successful with traditional strategies. Teachers tended to not think about assess-ment during their instructional planning and were not comfortable overlapping instruction and assessment (Kamen, 1996; Kaya, 2009). Experienced teachers, on the other hand, did begin to understand that instruction and assessment were linked and began to include different assessments in order to gain better information about their teaching. This was particularly evident in projects with a strong focus on helping teachers learn about assessments. For example, in a problem-based learning project, teachers were encouraged to use systematic observations and formal note taking of their students. Teachers reported that this made them recog-nize the integral relationship between assessment and instruction (Goodnough & Hung, 2009). In a more structured examination of assessment in the yearlong pro-gram mentioned earlier, teachers considered students’ responses in order to improve instruction and provide students feedback. This project also illustrates the level of challenge for teachers to understanding science assessment (Gearhart & Osmundson, 2009).

Progression. Assessments can be used to give grades, motivate students to work, and sometimes determine when to repeat material → Assessments can be used to see what students have correct (formal), see what students are thinking (informal), and provide feedback to students → Assessments can be used to understand what and how students are thinking about specific science ideas → Assessments are connected with instruction and should be used to inform instructional improvement

Again, experiences with students seemed to bring teachers’ attention to assess-ment in ways not seen in course work alone. Similarly, experience alone did not focus teachers’ thinking in ways seen when teachers were formally guided. Formally examining student work for the National Board Certification process pushed teachers to think about how to assess higher levels of thinking (Park & Oliver, 2008). Projects focused intensely on assessment and linked to students’ work for preservice or experienced teachers reported progress in teachers’ ideas about science assessment (Gearhart et al., 2006; Morrison et al., 2005).

Building a Picture

Overall, teacher thinking appears to progress first to thinking about learners, then to thinking about teaching, and finally to building a repertoire. Transitioning to a leader teacher was associated with more sophisticated thinking about teaching. Although it is likely that teachers who are more advanced in their thinking volun-teer or are recruited to be leaders, there was also some evidence that being a leader

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promotes more advanced thinking. Guidance and reflection appeared to be essen-tial. Time in the classroom alone was not sufficient for teachers to make progress. Indeed, hints of regression were uncovered when instruction for teachers was absent. When teachers reflected on practice and student responses, they had the opportunity to rearrange their ideas in ways that developed their science peda-gogical content knowledge. Formal learning opportunities such as ongoing pro-grams or graduate courses appeared to make a difference and move teachers along the trajectory toward more developed thinking. Uncoordinated professional devel-opment or, worse, no support for learning appeared to result in little progress. Longitudinal work was uncommon and much was reported regarding what teach-ers do and less regarding how they think about what they do. But more encourag-ingly, studies with small or large numbers of teachers presented consistent findings. Being able to include both small- and large-scale reports when looking across time frames aided the examination of data for trends and progress.

Discussion

Overall, this analysis indicates that it is helpful for teachers to think about learn-ers first, then to focus on teaching, and points out the essential role of reflection for teachers to rearrange their ideas in ways that develop their PCK (Henze, van Driel, & Verloop, 2008). This review also shows that although professional development opportunities are frequently provided for experienced teachers, these opportunities are not usually designed to build on previous experiences or to advance teacher understanding to higher levels. Thus, science teacher PCK reported for continuing teachers was often quite similar to PCK for earlier career teachers. More troubling are indications that PCK as defined by researchers might actually decline over time as teachers advance in their careers, highlighting the importance of advanced or extended professional development guided by the idea that teacher learning should progress across a profession. Using learning progressions as a framework for thinking about teacher learning illustrates that teacher educators have not created a careful curriculum for teachers across their careers in spite of the idea that teach-ers continue to learn and learn from their practice (Garet et al., 2001).

Learning Progressions for Science Teachers

Findings indicate that it is reasonable to think about learning progressions for teachers (Heritage, 2008). Teachers’ ideas did successively increase in sophistica-tion over a broad span of time. Progress, however, was not consistent or steady. This is likely due to the inconsistency of instruction rather than an inappropriate use of learning progressions or trajectories to describe teachers’ thinking. It was, in fact, possible to surmise trajectories for teacher learning when ideas about sci-ence teaching were disaggregated and examined. Using components of pedagogi-cal content knowledge as a lens made it possible to undercover a sequence of changes in teachers’ ideas. Because these trajectories were varied and sometimes included alternative paths, searching for desired outcomes as targets would not have been as helpful (Shavelson, 2009).

Progression of science teacher knowledge. When looking for evidence within each facet of PCK, some areas were found to be better represented than others. For

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example, research reports on teachers’ ideas about students’ initial ideas were more abundant while reports regarding teachers’ ideas about appropriate levels of under-standing were infrequent. Coverage was in part explainable by the trends in inter-est and the goals of the research community. Nature of science and misconceptions were two areas that were well populated, and information about teachers’ ideas about teaching science could be extracted. Other areas at first glance appear to be well represented, yet upon further examination were lacking description of teach-ers’ thinking. Assessment was an area where much is written but most is about what teachers do rather than what they understand. This is an important distinction when exploring teachers’ knowledge of science teaching in order to predict or influence what teachers might do (Darling-Hammond, Bransford, LePage, Hammerness, & Duffy, 2007). Moreover, topics of interest were given attention in educational opportunities provided for science teachers, and the goals of the research community often framed what was examined and reported. This is a lim-itation in describing learning progressions based on the available research find-ings. As ideas about what is important for science teachers to know evolves and characterizations of PCK are refined, it is likely that improved descriptions of teachers’ learning progressions will be possible.

Sequencing research reports by experience levels of the teachers studied was helpful but not perfect. Earlier career teachers such as preservice teachers tended to have certain ideas about teaching science. This is not surprising and is similar to the consistency seen in the reports of challenges for teachers new to inquiry (Davis et al., 2006). New teachers tended to have ideas that were similar to preservice teachers yet showed some development. More experienced teachers, on the other hand, might have the same ideas as early career teachers or they might have much more development. Leader teachers, even though these studies were a small sam-ple, were often the most likely to have the most sophisticated ideas. Leader teach-ers were not described as having early stage thinking in any PCK component. It is important to remember, however, that individual teachers were not followed. Thus, there appears to be a trend in the development of ideas but by no means do these trajectories describe any particular teacher’s progress.

Midcareer teachers, as well as illustrating novice ideas and more developed ideas, also illustrated ideas on a different overall path altogether. Specifically in the area of student thinking about science, two trajectories were suggested. Although true adaptive expertise was not obvious, trajectories in that direction were uncov-ered. For example, on one trajectory for development of student ideas, teachers became more responsive to students in their thinking. This might be in the direc-tion of adaptive expertise in that teachers were making choices for specific student needs. What is yet to be seen is how this level of thinking might develop in new or challenging situations (Bransford et al., 2006). On the other hand, some midcareer teachers showed evidence of moving in the direction of a form of routine expertise. Routines can be valuable, aiding teachers in managing classrooms and making it possible for teachers to actively think about students and learning. But routines are less helpful when they overshadow learning. For example, on the alternate trajec-tory for development of student ideas, teachers’ thinking progressed to presenting science ideas in ever smaller pieces to help students complete their work. Divergent trajectories were not seen in most areas of PCK examined in this review. But think-ing about types of expertise did uncover differences for midcareer teachers. This

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was not the case for early stage teachers, who tended to illustrate initial ideas, or for leader teachers, who tended to illustrate the most sophisticated ideas.

Influences on knowledge progression. Formal education was clearly helpful. For some components of PCK, concurrent science instruction was advantageous. The nature of science component of PCK is an example where studying science again was helpful. For inquiry strategies, science instruction that was intended for sci-ence teachers was more beneficial than traditional science coursework. A better understanding of science also impacted teachers’ ability to think about the nature of science ideas that would be challenging for students. This makes sense in that science content is considered an ingredient of PCK (Gess-Newsome & Lederman, 1999). But evidence also indicates that simply increasing science content was not as helpful as purposefully addressing inquiry or nature of science for learners. For other areas of PCK, thoughtful experiences with students were advantageous. For assessment, teachers’ thinking about strategies for assessing science appeared to depend first on work with students around assessment task, then on increasing the number of assessment strategies. In both examples—learning science and assess-ments in ways linked to students’ thinking—teachers’ learning is linked to stu-dents’ learning (Sykes, 1999). Throughout, reflection and instructional guidance were clearly and consistently supported as beneficial for teachers developing their thinking about teaching in productive directions (Ball & Cohen, 1999).

Implications for Research

There were very few longitudinal studies regarding teacher learning. In this review, only five studies followed teachers for more than 1 year. Although this is not surprising given the constraints of research with teachers, it is interesting given the acceptance of the idea that teachers’ learning takes place over the course of their careers (Feiman-Nemser, 2008). Yet, it was possible to build a picture of teacher learning by looking across studies. Even though different individuals par-ticipated in these studies, it was possible to extract overall trends or trajectories of teacher learning. As a field, longitudinal work should be supported and would improve descriptions of how teacher learning progresses. There is also a need for a greater focus on experienced teachers. Research on preservice teachers was ample and examined teachers at several points during the preservice year. Experienced teachers, on the other hand, were the focus of far fewer studies. Moreover, when experienced teachers were the subject of research they were com-monly grouped together rather than describing differences for teachers with some or more years of experience. More study of midcareer teachers and their learning would contribute to our understanding of how to support teachers more effectively (Moreland & Hobbs, 2011). Work to study leader teachers’ ideas about teaching science was rare. This is clearly an area in need of more work.

Pedagogical content knowledge is a popular yet still developing construct. Early work utilizing PCK to describe teachers’ ideas was relatively vague and undefined. Later work includes examples that are more analytical and descriptive. But, PCK is still a developing construct based on researchers’ and philosophers’ ideas about professional knowledge. What is described is, in part, related to the ideas and goals of the researchers themselves. More empirical work is needed to

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define this construct in a way that is useful for understanding and enhancing teach-ers’ knowledge. To this end, research that carefully describes what teachers know or their ideas about teaching science is needed. Across 25 years, fewer studies than might be expected actually examined teachers’ ideas for any specific component of PCK. One difficulty in this work is that PCK is defined as having many compo-nents, each with subcomponents. It is difficult to consider all facets within one study. As a field, attention to each aspect in a strategic fashion is needed. It also appears to be challenging for researchers to achieve a level that is not so general as to be closer to general pedagogical knowledge or so specific as to be closer to spe-cific content knowledge. Part of the attractiveness of PCK is that it is a domain of specific yet professional knowledge thought to be important for content teachers (in this case science) beyond their specific classroom. In this way, PCK can be a heu-ristic to guide our thinking about the development of adaptive expertise. Research framed by the idea that teachers’ thinking becomes increasingly sophisticated, whether longitudinal or at different points across profession, and that defines teach-ers’ thinking as knowledge of teaching subject matter that transcends individual classrooms would inform efforts to move teachers toward adaptive expertise.

Implications for Teacher Education

In the context of learning progressions for teachers, it is necessary to think broadly about teacher education. Educational opportunities for teachers need to begin with preservice education and continue with the same degree of concern for developing teachers’ thinking throughout their careers. In the studies examined for this project, professional development was not necessarily planned as a continuous experience. Teacher education to progress teachers’ learning and develop increas-ingly sophisticated thinking would build ideas over time and across educational opportunities (Garet et al., 2001). Given that teachers do not remain in any par-ticular program or school, developing coordinated programs across many years will be difficult. Yet, until such programs are developed, isolated sessions will likely have little lasting impact. Findings also indicate that programs need to pro-vide teachers with meaningful experiences with students before helping teachers build a larger repertoire of practices. The value of experience first was highlighted in studies looking at teachers’ ideas about assessment. In a similar fashion, these findings indicate that curriculum materials or requirements for teachers to design lesson plans could have a small set of ideas such as strategies for new teachers to practice initially with an increasing set of ideas and options as teachers develop their thinking about teaching science. Again, creating and coordinating different materials and requirements for new and experienced teachers will not be easy but may help teachers progress. Finally, it appears to be necessary to focus on peda-gogical content knowledge explicitly with clear opportunities for teachers to think about, experience, and reflect on how to think about each aspect of PCK (e.g., assessment) in relationship to students and science.

Conclusion

This review examines the research across 25 years, since the conceptualization of pedagogical content knowledge as a construct for teacher knowledge was introduced, for evidence of how science teachers develop pedagogical content

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knowledge. By using the framework of learning progressions, this review takes a unique approach to thinking about research on how and what science teachers learn. This work can support teacher educators in designing professional programs that support beginning and advanced learning for science teachers. In addition, because longitudinal studies are rare, a review across multiple studies with an eye for evidence that learning progresses from one professional stage to another can provide insight needed to create ongoing learning for science teachers. By looking across studies that examine PCK at different points along professional continuum, this review can inform efforts to design teacher education programs that reach across careers and highlight areas for further research. By looking across studies for patterns in how PCK develops over a career, we can begin to think about how to design programs and experiences that move teachers into advanced levels. This is key in understanding how to support continued growth by experience teachers.

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authorsREBECCA M. SCHNEIDER is an associate professor of science education and director of

secondary teacher education in the Judith Herb College of Education, Health Sciences, and Human Services at the University of Toledo, 2801 W. Bancroft St., Toledo, OH 43606-3390; e-mail: Rebecca.Schneider@utoledo.edu. Her design research is focused on science teachers’ thinking and their development as professionals with a special interest on supporting midcareer science teachers in continuing to learn as they take on new roles as mentors and leaders.

KELLIE PLASMAN is a doctoral student in curriculum and instruction in the Judith Herb College of Education, Health Sciences, and Human Services at the University of Toledo; e-mail: kellie.plasman@rockets.utoledo.edu. Her research interest focuses on the use of literacy in science education.