Science teacher education on nature of science through explicit and reflective curriculum development

This study applied a mixed-method with a quantitative pre-post-test design and the qualitative analysis of pre-service secondary science teachers’ (hereafter "the teachers") productions to answer some open questions about their answers to the test, which corresponds to an embedded design where the qualitative answer data-set provides a supportive role for the primary quantitative test data-set. The second author was the instructor, who delivered the resources, collected teachers’ data and productions, and continually assisted the teachers.

Participants

The participants were two cohorts of student teachers (24- to 29-year-olds), enrolled in the compulsory pre-service Master’s course to earn their license as secondary teachers. The cohorts included 10 and 9 teachers (6 and 4 women, respectively), who all have a degree in Physics (2, 1), Chemistry (5, 3), Environmental (2, 3), and Health Sciences (1, 2). However, the participants lacked prior teaching or professional experience, any NOS-related activity, even in the Master course, and were blind to the research design so that changes on NOS understanding may be attributable to the treatment.

Instruments

The study applies two research instruments: some didactic resources and the assessment tool. The resources are a set of documents delivered to teachers to scaffold their task, aimed at designing a Teaching Learning Sequence (TLS) on scientific investigations (the explicit global NOS issue for the TLS). The set involves a 7E-based template of the TLS, a short and simple reading on a science controversial historical case (the appendix shows an example), and some exemplary NOS instructional activities on the distinction between facts and explanations and group arguments concerning the reading (Vázquez, & Manassero, 2013b). Teachers were allowed to choose one out of six cases, ranging from Physics to Life Sciences: discovering a new planet, light duality, phlogiston and oxygen, moving continents, spontaneous generation, and pellagra (adapted from Suzuri-Hernandez, 2010). The labels of the lesson plan template are: title, abstract, target students, addressed NOS features, learning prerequisites (if any), school subject and curriculum content (to be infused), purpose and justification, learning goals, timing, methodological orientations, assessment criteria, materials and resources, and learning activities.

Planning lessons is a teachers’ basic activity of the Master’s course for their professional development. In this case, teachers must self-appropriate and draw inspiration from resources that were new for them, elaborate the learning demands, design and fill in the template, add new resources, make methodology decisions to develop their personal reflections about the resources provided on scientific investigations, and elaborate the TLS. The instructor presented the resources, assigned the tasks to the teachers, and gave continuous feedback and support, aimed at creating a positive disposition toward NOS teaching.

Table I. The ten questions applied as pre-test and post-tests to assess teachers’ NOS beliefs

*The first figure of the question number indicates the NOS dimension; for instance, first figures 1 and 9 of the key number indicate epistemic science themes; first figures 6 and 7 of the key numbers indicate social science themes.

The assessment tool is a standardized multiple-rating ten-item questionnaire that assesses teachers’ ideas about ten NOS issues (table I). The ten questions were selected from the pool Views on Science-Technology and Society (VOSTS) according to their fit with the NOS issues involved in the historical case readings (Table I, last column). The VOSTS is an empirically developed item pool with one hundred scenario-based questions; each question’s scenario displays a specific NOS issue (represented by a five-digit key number). A list of phrases (beliefs), each representing a reason to explain the NOS issue, follows the scenario (Aikenhead & Ryan, 1992; Manassero, Vázquez & Acevedo, 2001). The respondents rate their agreement (direct score) on each of the phrases within a question (multiple-rating) along a nine-point Likert scale (1 to 9, disagreement to agreement) but the respondents can also leave phrases unanswered to avoid forced choices.

The 9-point rating scale is purposefully broad to gain variance, reduce the problem of unequal ordinal intervals that short scales often display, and allow respondents’ refined answers. The sentences convey a range of different views, from informed to uninformed, which were classified in one out of three categories (adequate, plausible, naïve), which mirrors other previous triadic classifications for NOS statements (Abd-El-Khalick & Akerson, 2009; Liang et al., 2009). Thus, to obtain a homogeneous meaning for measurements, a rubric was applied to transform the phrases’ direct scores (1-9) into a new index measurement scale within the interval [-1, +1]. The processes of classification and rubric elaboration have been presented and applied elsewhere (Manassero, Vázquez & Acevedo, 2006; Vázquez-Alonso, Aponte, Manassero-Mas & Montesano, 2016; Manassero-Mas, Vázquez-Alonso & Bennàssar-Roig, 2016).

The rubric states a direct-code for adequate phrases (i.e., score 9 recodes as +1), a reverse-code for naïve phrases (i.e., score 1 recodes as +1), and an intermediate-code for plausible phrases (i.e., intermediate score 5 recodes as +1), and so on for the remaining scores, as is habitual in measurement scales. All indexes share a common meaning: the higher (or lower) the index, the better (or worse) informed is the respondent's NOS belief, according to the NOS experts’ current views. Thus, high positive indexes indicate informed beliefs (close to experts’ views), low negative indexes indicate misinformed beliefs (far from the experts’ views), whereas the intermediate index scores around 0 are transitional (Manassero et al., 2001; Vázquez et al., 2006; Vázquez-Alonso et al., 2016).

The new index scale provides a common meaning to all the questions and allows a fine-grained assessment: the set of sentence indexes of each question (NOS issue) provides the individual’s profile on the question, and the sentences’ mean provides a question index that indicates the respondents’ overall NOS understanding of each question (Manassero-Mas et al., 2016). This way, indexes offer high-quality assessment of NOS understanding, rich quantitative descriptions of individual understanding, and an accurate statistical analysis, as suggested by Lederman, Bartos and Lederman (2014, p. 991). Lederman, Wade, and Bell (1998, p. 610) considered VOSTS a valid and reliable instrument for the research of NOS beliefs, and many VOSTS items have been applied to assess teachers’ and students’ NOS understanding, where acceptable validity and reliability have been documented for large samples (Bennàssar et al., 2010; Vázquez-Alonso et al., 2016).

Finally, teachers’ qualitative reflections were independently graded by the researchers through simple rubrics, and solving some slight disagreements by consensus among the researchers.

Procedure

The intervention was designed to provide teachers with some explicit, purposeful, and planned opportunities for learning the NOS-targeted aspects through their own professional development. In the long term, it was aimed at making teachers aware of NOS, inducing favorable dispositions about teaching NOS issues, and encouraging and improving their NOS understanding through the previously adopted theoretical frameworks (learning as change and professional development), centered on teachers’ activities and reflections. The intervention was part of the regular assignments of the Master course, and particularly aimed at developing peer co-evaluation and self-evaluation (personal reflective thinking).

Initial pre-test assessment. Teachers answered the ten-question assessment tool that establishes the baseline of their prior NOS beliefs about scientific investigations (Table I). The tool triggers the teachers’ first personal reflections when providing their reflective answers.
Experimental treatment. This stage involved several intertwined part-time activities during three months (instructor’s guidance, teachers’ personal work, and group work) that deploy diverse opportunities to contact NOS concepts and goals through group discussions and personal activities and to make appropriate connections between prior knowledge and new concepts to teach NOS aspects (NOS pedagogy). The instructor explicitly presented the guidelines, documents, and activities; the Spanish NOS curriculum contents (scientific research) were made explicit, as these contents are mandatory for teachers, and the teachers were required to choose a specific secondary subject and a historical controversial scientific case (Table I) to contextualize their tasks (Manassero-Mas et al., 2018). The instructor related the curriculum and resources and presented the TLS template to the teachers, followed up the TLS elaboration, helped develop teachers' NOS beliefs and their reflective tasks, supervised work progress, organized teachers’ class presentations and discussions, and gave continuous feedback and support to focus tasks and create a positive disposition toward NOS teaching (Kattmann & Duit, 1998; Duit & Treagust, 2003). The teachers developed their lesson plans at their own pace, which enabled them to steadily prompt their reflective thinking (self-appropriation of resources, elaboration of learning demands, completion of TLS template, search for new resources, methodology decision-making, and TLS development), and to formalize and transfer their NOS ideas into their teaching practice. Next, the teachers presented, shared, and discussed their lessons, ideas, and experiences with their classmates (30 minutes), which provided additional reflective opportunities for receiving peers’ and instructors’ feedback, encouraging additional critical thinking, connections, and personal reflections.
Final assessment (post-test). Two weeks after completing the treatment, the ten questions were again answered by the teachers (blind to this design); the initial-final comparison allowed quantifying the impact of the treatment on teachers’ NOS understanding across the ten NOS issues (Table I).
The instructor elaborated the teachers’ initial and final answers to the questions and submitted them to the teachers, who were asked to write a personal reflection about the following topics:
- Explain the reasons that justify your answers in each question.
- Compare the initial and final responses to identify changes or continuity in each question and elaborate a reflection explaining and justifying the compared data.

On average, teachers spent about 15 hours of personal work and 5 hours of group presentation and discussion of the lesson plans. Additionally, the second cohort devoted two additional hours of a workshop, as some teachers spontaneously discovered the flowchart “How science works” and asked the instructor for group discussion (http://undsci.berkeley.edu/article/scienceflowchart). As the first cohort lacked this additional reflective workshop, the two cohorts have been treated separately to account for the effect of this factor.

The participants make up a natural convenience group of prospective science teachers (a small group to apply inferential statistics). Thus, the effect size statistic was applied to quantitatively assess the pre-post-test changes, that is, the differences between the mean index scores were computed in standard deviation units. The relevance criterion of the effect size (d>0.4) was applied to identify significant changes, whereas the effect size (-.10<d<.10) was considered as no change.

Question number*	Themes / sub-themes	Stem of the question (scenario)	Excerpts of the reading on spontaneous generation that are cues to the question theme
10113	Science as a process	The process of performing science is best described as ...:	This idea, often called "spontaneous generation", is quite understandable. For the next two centuries, the debate on spontaneous generation continued. As more and more observations accumulated against it, people gradually stopped believing in spontaneous generation.
60211	Scientists' characteristics	The best scientist always has an open mind, is impartial and objective in his/her work. These personal characteristics are needed to create better science.	Almost all scientists believed this explanation.
70221	Controversies/ fact-based closure	When a new scientific theory is proposed, scientists must decide whether or not to accept it. Their decision is based objectively on the facts that support the theory; it is not influenced by subjective feelings or personal motivations.	Redi concluded that non-living material does not produce living organisms. To prove this further, he put dead flies and dead worms onto meat inside sealed containers. No living maggots appeared in the containers with either dead flies or dead maggots. Redi was satisfied, but many others did not agree with him. As more and more observations accumulated against it, people gradually stopped believing in spontaneous generation.
70611	Universality of science/ scientists’ personality	Having the same basic knowledge, two scientists can develop the same theory independently of each other. The scientists’ character does NOT influence the content of a theory.	The Italian scientist Francesco Redi
70621	Universality of science / brilliant scientists	Some brilliant scientists like Einstein have a personal and unique way of seeing things. These creative points of view determine how other scientists in the same field interpret things.	… suspected that worms are produced by tiny, invisible eggs, laid by flies on the meat. Other insects, such as butterflies, lay eggs that become larvae before becoming adults.
90111	Observations and theoretical load	Scientific observations made by competent scientists will be different if they believe in different theories.	People saw that mice and rats suddenly appeared in the barns where the grain had been stored for a while. After waiting for a few days, Redi found that maggots appeared only in the open jars. He also saw how maggots eventually turned into flies.
90411	Fallibility and change	Although scientific investigations are correctly conducted, the knowledge that scientists discover through these investigations may change in the future.	In 1668, … A few centuries ago, people thought that grain could produce mice and rats. For the next two centuries, the debate on spontaneous generation continued.
90611	Scientific method	When scientists investigate, it is said that they follow the scientific method. The scientific method is:	Redi tested his idea by putting pieces of meat into a set of jars. He sealed some of the jars, put gauze over the tops of others, and left others open.
90621	Scientific research / utility	The best scientists are those who follow the steps of the scientific method.	He noticed that meat that is left for several days becomes full of maggots and thought the meat produces the maggots.
90631	Accumulative scientific research	Scientific discoveries occur as a result of a series of investigations, each one supported by the former and leading logically to the next until the discovery is made.	This idea agrees with the religious view that man is made of earth, and with the writings of Aristotle who said that all animals are formed from the four elements - fire, water, air, and earth. As more and more observations accumulated against it, people gradually stopped believing in spontaneous generation.