Suchergebnisse

In order to enhance teachers' professional awareness, it is necessary to understand and value their subjective or personal knowledge and beliefs. This study investigated the change of science teachers' personal knowledge about teaching models and modelling in science within the context of educational reform in the Netherlands. The study followed nine experienced science teachers during the first years of the implementation of a new syllabus, which emphasises models and modelling. Data collection consisted of the repeated administration of a Repertory Grid instrument. From the results, three different types of personal knowledge concerning teaching models and modelling in science were identified, each of which showed significant change over time. Type 1 combined modelling as an activity undertaken by students with the learning of specific model content. In Type 2 the learning of model content was combined with critical reflection on the role and nature of models in science. Finally, in Type 3, the learning of model content involved both students' production and revision of models, and a critical examination of the nature of scientific models in general. Implications for the teachers' professional development are discussed.

In science education, students should come to understand the nature and significance of models. In case of chemistry education it is argued that the present use of models is often not meaningful from the students' perspective. A strategy to overcome this problem is to use an authentic chemical modelling practice as a context for a curriculum unit. The theoretical framework for this strategy is activity theory rooted in sociocultural theories on learning. An authentic chemical modelling practice is characterized by a set of motives for model development through a well defined modelling procedure using only relevant issue knowledge. The aim of this study was to explore, analyse and select authentic chemical modelling practices for use in chemistry education. The suitability of the practices was reviewed by applying a stepwise procedure focussed on criteria such as students' interest and ownership, modelling procedure, issue knowledge and feasibility of the laboratory work in the classroom. It was concluded that modelling drinking water treatment and human exposure assessment are both suitable to serve as contexts, because both practices exhibit clear motives for model construction and the applied modelling procedures are in line with students' pre-existing procedural modelling knowledge. The issue knowledge involved is consistent with present Dutch science curriculum and it is possible to carry out experimental work in the classroom for model calibration and validation. The method described here to select and evaluate practices for use as contexts in chemistry education can also be used in other science domains.