The realisation of large scale curriculum renewals' key ideas in teachers' practices has a name of being problematic (e.g., Cuban, 1988; Doyle & Ponder, 1997; Coburn, 2003; Van den Akker, 1998; Fullan, 2007). A common way for curriculum evaluators to investigate the occurrence of this implementation problem is to examine, for a given curriculum renewal project or reform, how closely teachers’ practices subsequent to the renewal activities correspond to the practices that the developers had in mind. This study focuses on the coherence between what curriculum innovations aim at, and what teachers want and do, respectively between written and enacted curricula (Stein et al., 2007; Thijs & Van den Akker, 2009), over a period of several decades of renewals. We use a perspective inspired by metaphors from evolution theory and ecology. We call key ideas in those curricula curriculum intentions, and view them as memes, the cultural equivalent of genes (Dawkins, 1976/2016), expressed over decades in different curricula, as in ecosystems. This perspective is also inspired by Fullan’s Interactive factors affecting implementation (Fullan, 2007, p.87) and a practicality ethic as described by Doyle and Ponder (1973).

The study also explores what factors may have facilitated or hindered such curriculum intentions to be expressed in today's enacted curricula. Categories used to analyse influences on teachers' practices were inspired by the teacher agency model of Priestley et al. (2013).  

Central in this study is the case of upper secondary physics education in the Netherlands since 1970. Teachers in upper secondary education in the Netherlands have a great deal of freedom to shape their own curriculum, for example through the choice of textbooks and through the assessment of some of the national attainment targets in school-based exams. However, they are constrained by detailed national syllabi and exams, which cover 60% of the attainment targets.

Dutch physics education has been strongly influenced by science curriculum development projects in other countries, most prominently the American PSSC (Physical Science Study Committee) and Harvard Project Physics, the British Nuffield Science Teaching Project, and the German IPN’s Physik im Kontext. For these projects, as for Dutch projects, international literature on theories of knowledge and learning has also been influential.

The two research questions are the following:

1. To what extent do enacted curricula in upper general secondary physics education in the Netherlands reflect the intentions of renewals expressed in written curricula initiated since the 1970s?
2. What factors may have influenced the expression of the renewals’ intentions in teachers’ enacted curricula?

These questions reflect the aim of this study: to provide developers of large-scale curriculum renewals with insights that will help them organise the renewals so that their intentions are reflected in the enacted curricula. The study may also provide teachers with suggestions on how to influence large-scale innovations.

The curriculum intentions focused on had been identified in an analysis of six renewals since 1970. They are the following: Using contexts, Widening the scope of science education, Coordinating with other STEM subjects, Advancing concept development,and Advancing skills development.

The results of the analyses show that most of the renewals’ curriculum intentions have taken root in the teaching practices of most of the interviewed teachers. As prominent influencing factors appear: teacher education, continued professional development, previous classroom experiences, a diverse offer of resources, and, not surprisingly, the high-stake national exam system. Teachers' influence on renewals comes mainly from teachers participating as developers in renewal teams and from how developers process feedback from practising teachers.

The data show that the influences from unintended factors, including international projects and scientific literature, are not less significant than those from intended factors.

Some renewals studied for this case were projects, developing innovative practices and materials for teaching and assessment; others were formal reforms of the curriculum, laid down in legal standards. To answer the research questions, four qualitative substudies were conducted. The first two, addressing the first question, included analyses of written curricula and of interviews with 13 current teachers. Written curricula of renewals since the 1970s were analysed to identify curriculum intentions. Results were discussed by leading persons of those renewals since the 1970s in a participants’ conference. The report of that conference was used to validate the choice of curriculum intentions. To investigate current teachers’ practices, 13 teachers were interviewed: differing in experience with contributions to physics education other than that of teacher, in age groups, and in years of teaching experience. The teachers, in semi-structured interviews of about an hour, described their main activities during a characteristic lesson and the motivations underpinning those activities. The curriculum intentions validated in the participants’ conference were then traced in the teachers' responses about their enacted curricula, with the help of ATLAS.ti, using indicators for the curriculum intentions as codes. The third and fourth substudies went into the second question, about possible influences on the coherence between written and enacted curricula. Semi-structured interviews of about 45 minutes were conducted with the same 13 teachers, about direct influences they perceived, and with 17 participants and witnesses of the renewals, from the 1980s to the present, about influences they had perceived, exerted or observed. Also, curriculum documents and evaluations since 1970 were analysed. The data from the teacher interviews, indicating direct influences, were analysed, with coding categories from life history, professional history, values, beliefs, and structural and material incentives and constraints at various system levels. Within incentives and constraints, a distinction was made between the system of high-stakes national exams and syllabi, which are not adaptable for teachers, and adaptable elements such as school exams, projects, or professional development. For the analysis of the interviews with participants and witnesses of the renewals, and of documents from those years, the same categories as for the teacher interviews were applied for coding direct influences. Open coding was used to find categories of indirectly influencing factors: influences that do not affect teachers' practices in a way that teachers perceive directly. Each type of analysis was checked by supervisors and by a second coder.

Regarding coherence between written and enacted curricula, it appeared from the interview data that most of the investigated renewals’ curriculum intentions were expressed in the curricula enacted by current teachers. Only 'Coordinating with other STEM subjects' appeared in a very limited way. Regarding factors directly influencing the expression of the investigated intentions in enacted curricula: most interviewed teachers explained how their beliefs about effective teaching and values about the goal of physics education were predominantly influenced or reinforced by teacher education, continued professional development, or previous classroom experiences. Practices also appeared to be influenced by the variety of written and digital sources, and by national exams. Among indirectly influencing factors, theories about knowledge and learning, international curriculum examples, and social needs (e.g., equity or more STEM-professionals) were found. Unintended influences appeared to come from written texts, project teacher practices, networks and personal contacts. Intended approaches appeared to have influenced all elements of the teacher environment. Also, for all teachers, their possibilities of enacting curriculum intentions appeared to be affected by the national examination system: they prioritized preparation for those exams. A combination of safety (provided by school leaders, examination system, and sufficient time) and the availability of material and immaterial resources, emerges as a strong facilitator for offering teachers room for innovation. As indirect factor, also the influence of teachers on written curricula was found: from teachers participating as developers in renewal teams, and from the way developers processed feedback from practising teachers from earlier periods. The history of the Dutch physics curriculum has parallels with that of other science curricula, in and outside the Netherlands, but also contrasts, which would make it worthwhile to compare this study’s results with studies into those other curricula. However, studies with a similar scope have not been found yet.

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