Anita Wallin

On Developing Content-oriented Theories Taking Biological Evolution as an Example

Both in Europe and the United States there is a growing interest in design research. One example is the design and validation of topic‐oriented teaching–learning sequences. This research may be said to have two objectives. One is to design and test “useful products”, such as teachers’ guides and study material for students, which may be put into practice in various ways. The second is to contribute to the development of educational science; for example, understanding conditions for learning of given topics under regular classroom conditions. This article concerns the latter objective and deals with the development of content‐oriented theories stating conditions that promote learning with long‐term understanding of given topics. We present one such theory, concerning evolution by natural selection, and describe the arguments and evidence that underlie the theory, which we regard as a well‐founded hypothesis. Some methodological problems associated with testing this type of theory are discussed, as well as the role of content‐oriented theories in strengthening science education research as an autonomous specialization within educational science.

Discussing a Research Programme for the Improvement of Science Teaching

A research programme for the improvement of science teaching is described, exemplified, and discussed. Briefly, the idea of the programme is that researchers in science education and teachers in schools should work together to design teaching sequences and to assess how they function in practice. Research results concerning pupils’ everyday conceptions, as well as analyses of the conceptual structure of a given area and the reasons for teaching it, play an important role when working on a design. The most important product of the design phase is a detailed guide for teachers, which we look upon as a tool for further knowledge-building. In our paper we suggest that the idea of domain-specific theories is worth examining and developing. It might contribute to strengthening science education as an autonomous discipline.

The effect of exhalation flow on endogenous particle emission and phospholipid composition

Exhaled particles constitute a micro-sample of respiratory tract lining fluid. Inhalations from low lung volumes generate particles in small airways by the airway re-opening mechanism. Forced exhalations are assumed to generate particles in central airways by mechanisms associated with high air velocities. To increase knowledge on how and where particles are formed, different breathing manoeuvres were compared in 11 healthy volunteers. Particles in the 0.41-4.55μm diameter range were characterised and sampled. The surfactant lipid dipalmitoylphosphatidylcholine (DPPC) was quantified by mass spectrometry. The mass of exhaled particles increased by 150% (95% CI 10-470) for the forced exhalation and by 470% (95% CI 150-1190) for the airway re-opening manoeuvre, compared to slow exhalations. DPPC weight percent concentration (wt%) in particles was 2.8wt% (95%CI 1.4-4.2) and 9.4wt% (95%CI 8.0-10.8) for the forced and the airway re-opening manoeuvres, respectively. In conclusion, forced exhalation and airway re-opening manoeuvres generate particles from different airway regions having different DPPC concentration.