Teaching about nature of science through short lab activities in Hong Kong classroom

Nature of science (NOS) has been widely recognized as one of the major goals of science education by science educators and in many important science curriculum reforms and science standards documents (AAAS 1993; McComas and Olson 1998; NGSS Lead States 2013; NRC 2012). In the Next Generation Science Standards (NGSS) of the United States, nature of science is considered an important element closely associated with the Practices and Crosscutting Concepts (NGSS Lead States 2013). Despite decades of efforts in promoting it, disappointingly, NOS is still not an emphasized part of instruction in most science classrooms (Lederman 2007).

Among the common approaches to NOS teaching: generic NOS activities (Lederman & Abd-El-Khalick, 1998), historical and contemporary case studies, and lab investigations, lab investigations are most able to engage students personally to experience how science is working (Allchin et al., 2014). The NGSS (2013) states that 'students cannot comprehend scientific practices, nor fully appreciate the nature of scientific knowledge itself, without directly experiencing those practices for themselves.' (Executive summary, p.2).Despite the empirical evidence supporting the effectiveness of lab investigations in teaching about NOS (Deng et al, 2011), ordinary school lab activities are often limited in many ways for NOS learning. One commonly agreed problem is the lack of explicit attention to NOS aspects (Akerson, Abd-El-Khalick, & Lederman, 2000). Another important problem is that school lab activities are usually hugely different from authentic science (Chinn and Malhotra 2002), particularly in the East Asian regions. In an analysis comparing the PISA science performances of the top East Asian regions with their Western counterparts (Lau et al., 2015), East Asian regions (Hong Kong, Japan, Korea, Taipei and Macau) in general had less hands-on activities and investigations, and performed relatively weaker in identifying scientific issues. It seems that East Asian regions had not placed heavy emphasis on scientific investigations despite their top PISA performances, which is partly a result of the highly exam oriented culture of the East Asian communities. Hong Kong is the East Asian region having most hands-on activities and investigations, but the lab activities were still dominated by lab experiences and low-level cookbook experiments (Yip and Cheung 2004; Tsang 2004) that hardly foster students understanding of NOS.

It is against the above background that this study sets out to develop a new approach to NOS teaching using short lab activities that are ordinarily done and accepted by schools and teachers in East Asian regions. Clough (2006) contended that NOS instruction would be adopted by teachers when it only requires minor modifications of existing curriculum and teaching practices. Lederman and Lederman (2004) showed that ordinary school lab activities can be used for NOS teaching when the NOS aspects are explicitly attended to. Lau and Chan (2013) developed a new approach to NOS teaching called manipulated lab inquiry, where ordinary lab activities are modified to make particular NOS aspects salient so that students are engaged in deep and personal reflection of what science is. This study aims to further develop this approach for another important NOS aspect, underdetermination of scientific theory, and compare this approach with science case study in fostering students' NOS understanding.

There is wide consensus on the NOS aspects for science education: (a) tentativeness; (b) empirically based; (c) subjective as a human endeavor and theory-laden; (d) involving inference, imagination, and creativity; (e) socially and culturally embedded; and (f) developed from a combination of observation and inferences (Lederman, 2007; McComas & Olson, 1998). Tentativeness of science actually roots largely in underdetermination, which is that one can never determine if a scientific theory is absolutely true given a particular set of evidence. There could be alternative theories that can explain the evidence equally well. So the relation between theory and data is never certain but underdetermined. Underdetermination of scientific theory has constituted an important part of the nature of science because many attacks on the methodology of science arise out of it (Lauden 1990).

Manipulated lab inquiry for NOS learning

This approach aims to provide students with direct personal experience of how an NOS aspect is working during school lab inquiries. The first study of manipulated lab inquiry used a very common biology investigation in Hong Kong – how heat affects vitamin C contents of fruit juices, to target an important NOS conception, theory-laden observation (Lau & Chan, 2013). Students were first given two contrary theories about the inquiry: heat would or would not destroy vitamin C. They were then asked to find out the vitamin C contents in the heated and unheated juices using DCPIP titrations; indeed, all the juices were identical in vitamin C content. The interesting findings were that the groups holding the theory that heating would destroy vitamin C turned out finding greater differences in vitamin C content between the two samples than the groups being told that heating had no effects. In the post lab discussions, the students were surprised after finding that their experimental results had been biased by their 'theories' in mind, from which the concept of theory-laden observations was introduced and reflected upon. This pedagogical approach has captured the elements of the conceptual change model (Hewson et al. 1998) that a discrepant event is first used to confront learners' preconceptions and create cognitive conflicts, from which learners are guided to make sense of the informed conceptions. This approach is both explicit and reflective, the two elements considered to be at the heart of effective NOS teaching (Abd-El-Khalick and Lederman 2000). Moreover, compared to the decontextualized NOS activity using gestalt pictures (e.g. morphing man) (Lederman & Abd-El-Khalick, 1998), this approach illustrates theory-ladenness in the context of lab inquiry, which is likely more convincing to students that science is theory-laden (Clough, 2006).

Built on the above study, this study aims to provide further evidence for the manipulated lab inquiry as an effective approach to learning different NOS aspects. In this study, the investigation about the cause of apple browning was employed to show the underdetermination of scientific theory (Duhem 1954). A simple understanding of underdetermination is that one can never determine if a scientific theory is true given a particular set of evidence because other alternative hypotheses or theories could also account for the evidence equally well.