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In most secondary physics textbooks, waves are first introduced with examples of mechanical waves because they can be illustrated by drawings and photographs. However, these illustrations are static and cannot reflect the dynamic nature of waves. Although many mechanical waves (e.g. water waves and vibrating strings) can be easily shown using school apparatus, their motions are too rapid to observe clearly. Computer simulation is a solution but is not 'real'. This article describes how a consumer-type high-speed digital camera can be used visually slowing the motion of some wave experiments. Several techniques to further improve the visibility of the video content are also described.

In this article, we describe a simple method which can be used to measure the efficiency of a low power dc motor, a motor-converted dynamo and a coupled motor–dynamo module as a function of the speed of rotation. The result can also be used to verify Faraday's law of electromagnetic induction.

Teacher beliefs about curriculum design affect the quality of science education in schools, but science researchers know little about the interrelation of beliefs about alternative curriculum designs. This article describes a quantitative study of secondary science teachers' beliefs about curriculum design. A 33-item Science Curriculum Orientation Inventory (SCOI) was developed to measure five distinct orientations to curriculum: academic, cognitive processes, societycentred, humanistic, and technological. Data were collected from 810 integrated science, chemistry, physics, and biology teachers in Hong Kong. A confirmatory factor analysis of teacher responses to the SCOI indicated that science teachers' beliefs about curriculum design had a hierarchical structure; the five distinct curriculum orientations were positively correlated, forming a second-order curriculum, meta-orientation. Physics teachers were less society-oriented than biology, integrated science and chemistry teachers, and integrated science teachers were more humanistic than physics teachers. Although science teachers' beliefs about any of the five alternative curriculum designs did not vary with their teaching experience, the difference between beliefs about the cognitive processes orientation and the humanistic orientation increased when teachers had gained more teaching experience. Implications of these findings are discussed.