Changlong
Zheng
*,
Langsen
Li
,
Peng
He
and
Mengying
Jia
Institute of Chemical Education, Northeast Normal University, Changchun, Jilin 130024, China. E-mail: Zhengcl@nenu.edu.cn
First published on 27th October 2018
Although the content of science lessons has been analyzed from different perspectives by developing a set of codes (e.g., K. J. Roth, S. L. Druker, H. E. Garnier, M. Lemmens, C. Chen, T. Kawanaka, and R. Gallimore, (2006), Teaching science in five countries: results from the TIMSS 1999 video study, Washington, DC: National Center for Education Statistics), none of the existing coding systems have investigated it from a subject-specific and dynamic perspective. Aiming to fill this gap, this study develops a content coding map (CCM) to classify the content of chemistry lessons (CCL) into 12 types based on their roles and values. The CCM was constructed based on semi-structured interviews and revised by applying the initial CCM to six videotaped lessons. Furthermore, the coding was reviewed by an expert committee to confirm the content validity and evaluated by 86 in-service teachers using a questionnaire with responses measured on a five-point Likert scale to test for face validity. These 12 types of CCL were organized into five related groups in the CCM: core knowledge and practices (CKP), connections among CKP (C-CKP), expansion of CKP (E-CKP), scaffolding for CKP (S-CKP), and meaningless content in relation to CKP (MC-CKP). Each group is illustrated and discussed using specific types of CCL. The CCM, which provides a new way to explore chemistry classrooms, can be used as an analytic tool for chemistry educators to investigate the CCL and can serve as a guide for chemistry teachers when designing lessons.
The TIMSS used two video-based studies in 1995 and 1999 to investigate and describe teaching practices. These supplemented the TIMSS 1995 and 1999 student assessments. The TIMSS 1999 Video Study (Hiebert et al., 2003; Roth et al., 2006) focused on mathematics and science lessons in an attempt to discover national patterns and international variations using a large sample of teachers in various countries. A conceptual framework was developed with the aim of capturing the various features of science lessons (see Fig. 1). The TIMSS conceptual framework regarded the lesson as the center of the investigation and emphasized the coordination of Schwab's four commonplaces of teaching: the learner, the teacher, the milieu, and the subject matter (Schwab, 1969, 1971, 1973). As shown in Fig. 1, a lesson is a complex system that includes interactions among the students’ actions, the teacher's actions, and the science content. In addition, these aspects of a lesson system are shaped by the larger culture (Roth et al., 2006).
Fig. 1 Conceptual framework of the TIMSS 1999 Video Study (Roth et al., 2006). |
In light of the framework, the TIMSS 1999 Video Study developed a set of codes to analyze various features of the students’ actions, the teacher's actions, and the science content. In particular, the content of science lessons was divided into six areas, each with its own code: (a) content disciplines and topics; (b) types of science knowledge; (c) source of the science content; (d) content coherence; (e) challenge presented by the content; and (f) multiple sets and types of evidence. More specifically, the content discipline categories included earth science, life science, physics, chemistry, and other areas, whereas content topics were coded using the TIMSS Guidebook to Examine School Curricula (McNeely, 1997). Science knowledge was divided into six types based on the coding scheme: canonical knowledge, knowledge of real-life issues, procedural and experimental knowledge, classroom safety knowledge, nature of science knowledge, and metacognitive knowledge. There were four sources of science content: the teacher, textbook or workbook, worksheet, and other sources. Content coherence was divided into three categories: doing activities with no conceptual links, learning content with weak or no conceptual links, and learning content with strong conceptual links. The challenge presented by the content was classified into three levels by the coding team: challenging content, basic and challenging content, and basic content. Multiple sets and types of evidence were captured by three indicators: more than one set of first-hand data, more than one phenomenon, and more than one visual representation (Roth et al., 2006).
Although the TIMSS 1999 Video Study classified the selected content of science lessons, the subject specified by the selected content of the science lessons was not mentioned in their set of codes. Furthermore, Roth et al. (2006) investigated the content of lessons from multiple static perspectives. Thus, developing an appropriate coding scheme using a dynamic perspective, specifically within the chemistry discipline, will enable us to generate new insights into analyzing chemistry lessons. In light of the TIMSS conceptual framework and the classification of science content, this study aims to develop a discipline-specific CCM to analyze the CCL.
Previous studies in the domain of chemistry education have developed various rubrics, coding schemes, or protocols to investigate classrooms, mainly focusing on two aspects: students’ actions and teachers’ actions. For example, regarding students’ actions, Crujeiras-Pérez and Jiménez-Aleixandre (2017) developed a rubric to analyze students’ planning investigations in the chemistry laboratory, Kulatunga et al. (2013) constructed a coding scheme to investigate the features of student group argumentation in a general chemistry course, and Seng and Hill (2014) established a coding scheme to identify several categories of peer feedback during chemistry investigative task discussion. In terms of teachers’ actions, Nehring et al. (2017) constructed two model-based coding schemes to investigate the complexity of teachers’ questions during chemistry instruction, while some studies (e.g., Herrington et al., 2011; Yezierski and Herrington, 2011) used the Reformed Teaching Observation Protocol to evaluate chemistry teachers’ instructional quality. Furthermore, several studies regarded the teacher and students as a unified system and developed coding schemes to investigate chemistry classrooms including both the students’ actions and the teacher's actions. For instance, Fay et al. (2007) constructed a rubric to distinguish among levels of inquiry in the undergraduate chemistry laboratory, which provided a standard for examining the laboratory curriculum, while Philipp et al. (2014) developed a protocol to evaluate the use of representations in secondary school chemistry lessons. Nevertheless, none of the existing coding schemes focuses on the lesson content, which is identified as an important element of lesson analysis in the TIMSS conceptual framework. Therefore, developing a CCM to classify the CCL should help to fill this gap in the literature.
Each lesson in Chinese secondary schools contains a variety of content. In this regard, chemistry lessons can be divided into several “primitive units” that present fundamental content for further analysis. A primitive unit is a single concept related to either core knowledge or practices in which the teacher defines, states, describes, demonstrates, illustrates, explains, provides examples, or reviews a concept or skill. The following transcript provides an example of a primitive unit.
[Teacher] OK. Based on the conduction experiment, we know that some chemical compounds ionize and generate free-moving ions. Can somebody tell me whether the ionization is a chemical reaction?
[Teacher] What is the definition of a chemical reaction? Think about it in terms of the chemical bond.
[Student 1] Old bond breaking and new bond forming.
[Teacher] Then is the process of ionization a chemical reaction?
[Students] No.
[Teacher] Not a chemical reaction. The process of ionization only breaks the old bond without forming a new bond.
This primitive unit can be described as a discussion between a teacher and his/her students on the definition of a chemical reaction to confirm that ionization is not a chemical reaction. The present study strictly focuses on the content of each primitive unit which is regarded as the CCL. The CCL in the above episode can be labeled as “understanding ionization by reviewing the definition of a chemical reaction.” This study divides chemistry lessons into several primitive units, the content of each corresponding to one CCL.
Iterative preliminary interviews were conducted to develop the following interview questions:
(1) What kinds of CCL do teachers present in teaching secondary school chemistry?
(2) What are the roles and values of these CCL?
(3) How do you classify these CCL in terms of their roles and values?
Given these questions, all interviewees were asked to watch a videotaped chemistry lesson, after which they answered the questions in the context of the content-specific lesson. Their views on the roles and values of the CCL were labeled as an indicator pool for the initial CCM. All interviews were video-recorded and transcribed verbatim, and permission was obtained from all interviewees for the interviews to be used in this study. The development of this initial CCM was undertaken iteratively by analyzing the results of the interviews. The initial CCM, with 16 types of CCL, is presented in the first column in Table 1.
Types of CCL (initial version) | Types of CCL (final version) | Treatments |
---|---|---|
Note: to differentiate between the initial and final versions, we have attached asterisks to the initial items (e.g., CKP-1*). CKP = core knowledge and practices; C-CKP = connections of CKP; S-CKP = scaffolding for CKP; E-CKP = expansion of CKP; MC-CKP = meaningless content in relation to CKP. | ||
CKP-1* Chemistry core knowledge as the main properties of typical chemical substances | CKP-1 Chemistry core knowledge as the main properties of typical chemical substances | — |
CKP-2* Chemistry core knowledge as concepts, theories, and laws | CKP-2 Chemistry core knowledge as concepts, theories, and laws | — |
CKP-3a* Chemistry core practices as laboratory skills | CKP-3 Chemistry core practices as basic skills | Revised (combine laboratory skills, chemical symbol representation skills, and stoichiometry as the basic skills of chemistry) |
CKP-3b* Chemistry core practices as chemical symbol representation skills | ||
CKP-3c* Chemistry core practices as stoichiometry | ||
CKP-4* Chemistry core practices as scientific inquiry | CKP-4 Chemistry core practices as scientific inquiry | — |
C-CKP-1a* Explanations of chemical-related phenomena using chemistry core knowledge and practices | C-CKP-1 Applications of chemistry core knowledge and practices | Revised (combine explanations of phenomena and problem-solving in the applications of core knowledge and practices) |
C-CKP-1b* Chemical-related problem-solving using chemistry core knowledge and practices | ||
C-CKP-2* Clarifying the connections among chemistry core knowledge and practices | C-CKP-2 Systematic networks between chemistry core knowledge and practices | Revised (modify expression to be more concise) |
S-CKP-1a* Chemical-related evidence scaffolding for students learning chemistry core knowledge and practices | S-CKP-1 Directly supporting students’ learning of chemistry core knowledge and practices | Revised (combine chemistry evidence and theoretical reasoning as direct support for students’ learning, corresponding to indirect support in S-CKP-2) |
S-CKP-1b* Chemistry theoretical reasoning scaffolding for students learning chemistry core knowledge and practices | ||
S-CKP-2* Stepping stones for students learning chemistry core knowledge and practices | S-CKP-2 Indirectly supporting students’ learning of chemistry core knowledge and practices | Revised (modify the expression to correspond to S-CKP-1 and provide more clarity) |
E-CKP-1a* Explanations to help students’ understanding of chemistry core knowledge and practices | E-CKP-1 Promoting students’ understanding of chemistry core knowledge and practices | Revised (combine teachers’ explanations and illustrations to promote students’ learning) |
E-CKP-1b* Illustrations to assist students’ understanding of chemistry core knowledge and practices | ||
E-CKP-2* Extensions of chemistry core knowledge and practices | E-CKP-2 Reasonable extensions of chemistry core knowledge and practices | Revised (extension was classified into reasonable and unreasonable parts) |
MC-CKP-1* Inappropriate content for learning chemistry core knowledge and practices | MC-CKP-1 Inappropriate content for learning chemistry core knowledge and practices | — |
— | MC-CKP-2 Unreasonable extensions of chemistry core knowledge and practices | Added (derived from E-CKP-2*) |
Types of CCL | Lesson | Total | Percentage (%) | |||||
---|---|---|---|---|---|---|---|---|
Sodium | Aluminum hydroxide | Ionization | Reaction rate | Primary battery | Proteins | |||
Note: CKP = core knowledge and practices; C-CKP = connections of CKP; S-CKP = scaffolding for CKP; E-CKP = expansion of CKP; MC-CKP = meaningless content in relation to CKP. | ||||||||
CKP-1* Chemistry core knowledge as the main properties of typical chemical substances | 6 | 3 | 4 | 4 | 3 | 3 | 23 | 15.75 |
CKP-2* Chemistry core knowledge as concepts, theories, and laws | 1 | 0 | 3 | 1 | 1 | 2 | 8 | 5.48 |
CKP-3a* Chemistry core practices as laboratory skills | 1 | 0 | 1 | 0 | 1 | 0 | 3 | 2.05 |
CKP-3b* Chemistry core practices as chemical symbol representation skills | 0 | 1 | 1 | 1 | 1 | 0 | 4 | 2.74 |
CKP-3c* Chemistry core practices as stoichiometry | 0 | 0 | 0 | 2 | 0 | 0 | 2 | 1.37 |
CKP-4* Chemistry core practices as scientific inquiry | 1 | 1 | 2 | 1 | 2 | 0 | 7 | 4.79 |
C-CKP-1a* Explanations of chemical-related phenomena using chemistry core knowledge and practices | 0 | 0 | 2 | 1 | 2 | 3 | 8 | 5.48 |
C-CKP-1b* Chemical-related problem-solving using chemistry core knowledge and practices | 0 | 3 | 0 | 1 | 0 | 0 | 4 | 2.74 |
C-CKP-2* Clarifying the connections among chemistry core knowledge and practices | 5 | 2 | 3 | 1 | 1 | 2 | 14 | 9.59 |
S-CKP-1a* Chemical-related evidence scaffolding for students learning chemistry core knowledge and practices | 2 | 0 | 1 | 1 | 2 | 0 | 6 | 4.11 |
S-CKP-1b* Chemistry theoretical reasoning scaffolding for students learning chemistry core knowledge and practices | 1 | 0 | 0 | 0 | 1 | 2 | 4 | 2.74 |
S-CKP-2* Stepping stones for students learning chemistry core knowledge and practices | 6 | 3 | 3 | 2 | 3 | 3 | 20 | 13.70 |
E-CKP-1a* Explanations to help students’ understanding of chemistry core knowledge and practices | 2 | 4 | 5 | 4 | 5 | 3 | 23 | 15.75 |
E-CKP-1b* Illustrations to assist students’ understanding of chemistry core knowledge and practices | 0 | 1 | 2 | 0 | 2 | 1 | 6 | 4.11 |
E-CKP-2* Extensions of chemistry core knowledge and practices | 0 | 1 | 2 | 0 | 1 | 2 | 6 | 4.11 |
MC-CKP-1* Inappropriate content for learning chemistry core knowledge and practices | 0 | 2 | 0 | 2 | 1 | 3 | 8 | 5.48 |
Total | 25 | 21 | 29 | 21 | 26 | 24 | 146 | 100.00 |
From Table 2, it can be seen that the percentages of some types of CCL, such as CKP-3a*, CKP-3b*, and CKP-3c*, were less than 5%, which means that those types may not emerge frequently in secondary school chemistry lessons. Therefore, two rules were applied to refine the initial CCM: the percentages of all types of CCL should be higher than 5%, and some types of CCL with low percentages can be combined based on their similar roles and values. For example, we combined CKP-3a*, CKP-3b*, and CKP-3c* into a single type of CCL, CKP-3, which had a percentage of 6.16%. The details of the treatments and changes can be seen in Table 1. In particular, we further divided E-CKP-2* into E-CKP-2 and MC-CKP-2 because not all extensions of chemistry CKP are reasonable. After reviewing all six lessons, the statements and number of indicators were revised to reflect the context of the chemistry lessons.
To guarantee the face validity of the final CCM, a questionnaire was distributed to 86 in-service chemistry teachers who were undertaking a national professional development program, and who were willing to provide their opinions voluntarily. Responses were measured on a five-point Likert-type scale where 5 = “Strongly agree” and 1 = “Strongly disagree”. Teachers from 27 provinces in China were selected by their local education bureau as outstanding representatives of their profession. Details regarding the demographics of these teachers are presented in Table 3.
Frequency | Percent (%) | |
---|---|---|
Gender | ||
Female | 41 | 47.7 |
Male | 45 | 52.3 |
Total | 86 | 100.0 |
Teaching years | ||
1–5 | 4 | 4.7 |
6–10 | 10 | 11.6 |
11–15 | 20 | 23.3 |
16–20 | 17 | 19.8 |
21–25 | 22 | 25.6 |
26–30 | 11 | 12.8 |
31–35 | 2 | 2.3 |
Total | 86 | 100.0 |
Region | ||
North China | 10 | 11.6 |
Northeast China | 6 | 7.0 |
East China | 24 | 27.9 |
South Central China | 21 | 24.4 |
Northwest China | 10 | 11.6 |
Southwest China | 15 | 17.4 |
Total | 86 | 100.0 |
Responses of “Strongly agree” (5) and “Agree” (4) indicated that the respondents agreed with the category for CCL, responses of “Strongly disagree” (1) and “Disagree” (2) indicated that they did not agree with the category for CCL, and a response of “Neutral” (3) meant that they were unsure. Scores above 3 were taken to signify their agreement with the rationality of the coding items (Arends-Tóth et al., 2006). The mean score and standard deviation were calculated for each item and are presented in Fig. 2. It can be seen that the mean scores for 11 of the 12 items were higher than “Agree” (4), and even the lowest mean score (for item E2) was above the midpoint. These responses provide strong evidence supporting the final CCM. Thus, the final CCM items (see the second column in Table 1) were determined.
Factual knowledge, which is labeled CKP-1, refers to the main properties (e.g., redox properties and acid–base properties) of typical chemical substances (e.g., sodium and aluminum hydroxide). Conceptual knowledge, which is labeled CKP-2, includes chemical concepts (e.g., electrolysis and ionization), theories (e.g., atomic theory and transition-state theory), and laws (e.g., the ideal gas law). Factual and conceptual knowledge can be combined to form chemistry core knowledge, which summarizes what is important for students to know, including the facts, concepts, theories, and laws of chemistry.
In addition to this knowledge, the chemistry skills, which are labeled as CKP-3, that were mentioned by the NCCSJHS (Chinese Ministry of Education, 2017) include laboratory skills (Taber, 2016), chemical symbol representation skills (Wang et al., 2017), and stoichiometry (Gulacar et al., 2013), for instance, configuring solutions, writing ionic equations, and calculating reaction rates. Moreover, the NCCSJHS emphasized the importance of scientific inquiry, which is labeled as CKP-4, in the list of content requirements. To be specific, under the topic of Chemistry and experimental inquiry, the NCCSJHS stated that students should “know the key elements of the process of scientific inquiry such as asking questions, proposing a hypothesis…constructing conclusions, and evaluating findings” (p. 12). Thus, scientific inquiry should be regarded as a vital component of chemistry lessons (Herrington et al., 2011; Vhurumuku, 2011). For example, a teacher guided students in exploring the factors influencing the reaction rate by designing and analyzing a controlled trial. Considering that chemistry skills and scientific inquiry are relevant to real-world practice, they should be integrated into the core chemistry practices, which include what is important for students to do.
Several studies noted that connections to real-life contexts (i.e., C-CKP-1) were important in helping students to retain knowledge (e.g., Talanquer and Pollard, 2010; Broman and Parchmann, 2014; Eilks and Byers, 2015). Based on the level of difficulty of questions posed, applications of chemistry CKP can be divided into two levels: low-order and high-order. In most lessons in Chinese secondary schools, applications usually involve the transfer of CKP to a simple question or problem, which is regarded as low-order application. For example, after the teacher introduced the components and mechanism of a primary battery, the teacher provided two redox reactions and students were asked to “design two primary batteries with these two reactions and draw the device diagrams on the draft paper” (teacher of primary battery lesson, video-recorded lesson). This type of application aims to “give students a chance to become familiar with the knowledge we (teachers) have talked about and the students’ performances can be seen as feedback for me to evaluate whether I taught it clearly” (expert teacher, interview).
In terms of high-order applications, one chemistry educator stated that “our daily lessons are full of simple applications instead of high-order and integrated applications…some of the better schools would spend a specific amount of time during a semester designing project-based learning or problem-based learning” (chemistry educator, interview) and high-order applications exist in these particular learning processes. High-order applications, which are an effective “catalyst” for student progress, refer to complex and challenging problems in an unfamiliar situation. For example, the teacher might assign a task requiring students to modify a dry cell battery after introducing the concept of dry cell batteries. Nevertheless, these high-order applications are seldom used in the context of chemistry education in mainland China, and we did not find any high-order applications in the sample lessons used in this study.
Regarding C-CKP-2, a systematic network involves the establishment of relationships in the conceptual world. Previous studies (e.g., Whitehead, 1959; Bodner, 2007; Johnstone, 2009) have indicated that chemistry students face the challenge of “being able to see the woods while avoiding being lost in the trees.” Some students only memorize isolated clusters of chemistry CKP, and thus are less likely to retain the CKP and transfer them to complex problems. In this case, connecting the isolated CKP into systematic networks in classrooms (i.e., C-CKP-2) is useful in enabling students to construct an integrated chemistry world. In Chinese secondary schools, C-CKP-2 generally emerges after students have grasped the CKP, and acts as a supplement or summary that helps to strengthen the students’ understanding. In one of the video-recorded lessons, a summary at the end of the lesson provided a good example.
[Teacher] OK! Let us go back to the question at the beginning. What are the factors influencing the reaction rate?
[Student 1] Temperature and concentration
[Student 2] Pressure and surface area
[Teacher] Anything else?
[Student 2] Catalysts
[Teacher] Ok! Can anybody tell us what the relationships are between these factors?…The occurrence of a chemical reaction can be regarded as a certain amount of particles having a certain energy colliding with each other. The reaction occurs when the collision process reaches the energy required for the reaction to occur…Temperature affects the energy of the particles. These three factors (concentration, pressure, and surface area) influence the number of particles that may participate in the reaction. In terms of the catalyst, it affects the energy required for the reaction to occur. (teacher of reaction-rate lesson, video-recorded lesson)
This episode showed a teacher helping students to understand the relationships between various factors influencing the reaction rate, so that students did not merely remember isolated factors. What should be noted here is that the networks are hierarchical. The example we provided clarified the relationships between five elements involved in one concept (i.e., the factors influencing the reaction rate). High-level networks such as relationships between different concepts (e.g., chemical equilibrium and the reaction rate) or even big ideas (e.g., energy and reactions) were suggested. With all these aspects in mind, assisting students in forming systematic conceptual networks is an indispensable part of teaching in chemistry classrooms.
More specifically, S-CKP-1 contains both evidentiary support and theoretical support. Evidentiary support refers to the data used by teachers to support students’ understanding of CKP. The forms these data take mainly include the process and results of classical experiments (e.g., Rutherford's gold foil experiment), existing data (e.g., the melting points for various metals), and experimental data from actual observations and measurements by students (e.g., the pH of various solutions). These data “can be used as scaffolding to build conceptual understanding in chemistry” (Nichol et al., 2014, p. 1318). For example, a teacher conducted an experiment to support students’ understanding of the properties of sodium. The details were as follows.
[Teacher] What happens to sodium when it encounters water?…Take a small piece of sodium and use filter paper to suck up the kerosene, and then put it into water that has been added to phenolphthalein. The reaction between sodium and water is intense, so we must strictly control the amount of sodium. [Teacher puts the sodium into the water]
[Students] Wow!
[Teacher] What have you observed?
[Student] It swims randomly.
[Teacher] And?
[Student] The water turns red.
[Teacher] Anything else?…Pay attention to the position of the sodium. You can see it floating on the water. And look at its shape. It has melted into a ball…Why did these things happen? (Teacher of the sodium lesson, video-recorded lesson)
Swimming, reddening, floating, and melting were the qualitative data that provided students with a better opportunity to fully understand this reaction and the chemistry involved compared with just a verbal description. In addition to qualitative data, quantitative data are also commonly used in chemistry lessons. For example, Glazier et al. (2010) used data on boiling points to support students’ learning in relation to intermolecular forces. Evidentiary support “offers several significant advantages in assisting teachers to focus on concept development” (Nichol et al., 2014, p. 1318). As for theoretical support, this refers to the fundamental theories used to support students’ learning. For instance, simple collision theory was introduced by a teacher to support students in understanding the factors influencing the reaction rate. In conclusion, these types of support (i.e., S-CKP-1) “are essential for students to construct new concepts” (expert teacher, interview).
S-CKP-2 refers to the content that paves the way for learning CKP, whereby values and roles are designed to help the learning process occur as a smooth transition. For example, the teacher introduced the importance of proteins and the origin of the word “protein” to indirectly support students in learning the properties and structures of the various proteins (i.e., the CKP). The details were as follows.
[Teacher] The food we eat every day not only provides us with sugar, as we learned before, but also supplies us with proteins. Proteins are an essential component of our cells and are necessary for regeneration and functioning. They were first discovered in the 19th century, and scientists regarded them as the essence of life, so they were named after the Greek word “proteions,” meaning first or primary. (teacher of proteins lesson, video-recorded lessons)
This part of the lesson was the prelude, and was labeled as indirect support in this study because it helped students to construct the CKP related to proteins. In this case, compared with direct support (i.e., evidence and basic theories), there is a relatively weak correlation between indirect support and the construction of CKP. With all this in mind, S-CKP-1 is like a “pillar” (expert teacher, interview) and S-CKP-2 is like a “stepping stone” (expert teacher, interview), which together are regarded as scaffolding to support students’ learning.
More specifically, E-CKP-1 means that teachers promote students’ deeper understanding of CKP. The format for this type of CCL mainly includes explanations or illustrations by the teacher. For example, textbooks define an electrolyte as any compound that conducts electricity when melted or dissolved in water, but one teacher explained an electrolyte as “any compounds that break their chemical bonds and form ions owing to the energy released by melting or dissolving in water” (teacher of ionization lesson, video-recorded lesson). The definition in the textbooks captures the electrolyte from a macroscopic perspective, whereas the teacher explained it at the microscopic level. These kinds of explanations are useful for promoting and deepening students’ understanding of CKP. Since chemistry always adopts various models and theories to explain empirical data (Carr, 1984; Taber and Watts, 2000) or uses microscopic entities to explain the macroscopic world (Johnstone, 2000; Tümay, 2016), insightful explanations or illustrations often appear in chemistry classrooms. As shown in Table 2, the percentage of E-CKP-1 was 19.86% over the six video-recorded lessons. Teachers “pay great attention to explanations or illustrations” (expert teacher, interview) for promoting students’ learning.
E-CKP-2 refers to reasonable extensions of CKP that are not highlighted by the curriculum standards but are nonetheless conducive to students’ understanding of CKP. For example, after learning about the differences between reactions involving sodium and oxygen under different conditions (i.e., room temperature and higher temperatures), the teacher added that “the product of a reaction between lithium and oxygen is always lithium oxide, regardless of whether the reaction occurs at room temperature or at higher temperatures” (teacher of the sodium lesson, video-recorded lessons). The lack of differences in the reaction between lithium and oxygen under different temperatures is not mentioned in the standards document but can be used as a comparison with the outcomes of reactions between sodium and oxygen to enrich students’ learning in terms of reactions between alkali metals and oxygen, which is considered a reasonable extension. This type of CCL is appropriate for enriching students’ conceptual breadth.
As for MC-CKP-2, this involves unreasonable extensions that do not help students to understand CKP. For instance, following the experiment that involved heating sodium, one student noticed that the resulting yellow product was accompanied by some black material and asked the teacher what it was. In responding, the teacher paid too much attention to explaining the insufficient combustion of kerosene. The aim of the experiment was to provide qualitative data for students to support their understanding of the properties of sodium, and the teacher should simply have responded to the student's question by, for example, stating that “the black material is the impurities from the kerosene combustion, and students who are interested in this can investigate it further after class,” instead of providing an elaborate explanation of the process of producing the black material, which was regarded as an unreasonable extension.
With all this in mind, a discipline-specific and dynamic perspective is the highlight of this study. Chemistry educators can use the CCM as an analytic tool to analyze the content of chemistry lessons, while chemistry teachers, especially those who only have a little teaching experience, can use the CCM to guide them in selecting and organizing the CCL.
The analysis of CCL include three main aspects: frequency (i.e., the proportion of each type of CCL in lessons), arrangement (i.e., the sequence of different types of CCL), and time allocation (i.e., the time spent on different types of CCL). With the aim of exploring the appropriate allocation of time to different CCL, future research can be undertaken wherein a large sample of high-quality (i.e., award-winning) lessons is collected and analyzed in terms of time allocation. In addition, these high-quality lessons can be used to investigate patterns in terms of frequency and sequencing to identify whether there are more effective ways of selecting and organizing the CCL. Any patterns that emerge from a study of these high-quality lessons will not only support chemistry teachers in their lesson design but also provide a benchmark for chemistry educators when evaluating lessons.
In terms of future research, after developing the CCM, one question that was raised in the Introduction section remains unanswered: what kinds of teaching behavior are appropriate for various types of content? This is a vital factor influencing the effectiveness of teaching (Zheng et al., 2014; He et al., 2016). Using the classifications in this CCM, the relationship between teaching behaviors and types of CCL should be investigated in future studies with the aim of identifying the most effective mode of classroom teaching.
Moreover, future studies should apply this CCM to analyzing the links between content patterns of chemistry lessons and various factors such as culture, teaching experience, curriculum materials, and the level of the teachers’ pedagogical knowledge.
In summary, this study developed a CCM that enables the analysis of the CCL in Chinese high schools from a subject-specific and dynamic perspective. The development and validation process used to create this CCM might be applicable to other science disciplines such as physics and biology.
This journal is © The Royal Society of Chemistry 2019 |