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

The findings of the study show that both manipulated lab inquiry and scientific case study are effective in fostering students' understanding that scientific conclusions and theories are tentative and not truth because of the underdetermination between data and theories. Manipulated lab inquiry is superior to scientific case study in that the NOS learning can be transferred across contexts - from the apple browning experiment to the case of dinosaur extinction, whereas scientific case study has its effects more limited to its teaching context. Alternatively, we can construe the findings as manipulated lab inquiry having effects on both the practical and formal epistemologies of students (Sandoval 2005). The superiority of manipulated lab inquiry over scientific case study likely stems from the personally reflective experiences provided to students. These findings, in couple with that of the first study on manipulated lab treatment (Lau and Chan 2013), have provided empirical support to manipulated lab inquiry as a potentially fruitful and efficient way of NOS teaching in secondary classroom. The manipulated lab inquiry, however, is better conducted in connection scientific case study so that students would not discount the learning as a school 'game' and can transfer their understandings to authentic science (Crawford, 2012). This is what Clough (2006) advocates to move along the continuum from the decontextualized, to school lab to authentic contexts, where students would have their NOS conceptions consolidated and expanded.

The value of this approach to NOS teaching is that it only needs a little modification of ordinary, short school experiments, which makes it likely adopted by frontline teachers and schools in East Asian regions where exam pressure and overemphasis on content learning form the major hindrance to NOS teaching in spite of decades of efforts in promoting it. Moreover, the manipulated lab inquiry can also be used for learning a variety of concepts and skills beyond the NOS aspects. The NGSS encourages nature of science, science practices and crosscutting concepts to be learned in an integrated manner, and the apple browning investigation can serve these ends as shown in Table 6. When scientific investigations can be conducted in this manner with explicit focuses on science processes and NOS understandings, the performance of East Asian regions in procedural and epistemic knowledge of science as assessed in PISA 2015 would be enhanced.

Table 5. Connections of the apple browning investigation with science practices, nature of science and crosscutting concepts of NGSS.

Investigation of apple browning	Science practices	Nature of science	Crosscutting concepts
Students discuss under what conditions an apple would turn brown		Scientific knowledge assumes an order and consistency in natural systems Science addresses questions about the natural and material world	Patterns
Students propose hypothesis for the cause of apple browning	Asking questions (propose testable questions for investigation)		Cause and effect (multiple hypothesis)
Students design experiment to test the two hypotheses - browning due to oxygen exposure or due to enzyme actions.	Planning and carrying out investigations (identify independent and dependent variables, control confounding variables, measure variables accurately, etc.)	Scientific knowledge is based on empirical evidence Scientific investigations use a variety of methods
Students analyze and present the results	Analyzing and interpreting data Constructing explanation
Students are engaged in argument about which of the two hypotheses is correct based on the evidence, and what further evidence is needed to draw a conclusion.	Engaging in argument from evidence Constructing explanation	Scientific knowledge is based on empirical evidence Scientific knowledge is open to revision in light of new evidence (e.g. underdetermination of scientific theory, errors and uncertainties of data) Science is a Human Endeavor (e.g. human judgement needed to make conclusion)	Cause and effect (multiple causes)

Nonetheless, the conclusions have to be taken cautiously in view of the limitations of the study: small sample size and no delayed post-test. The conclusions may be limited to the contexts of the study only. Further study is needed to develop and validate the manipulated lab inquiry approach in various contexts of school experiments that target different NOS aspects, and assess its effects in longer period through longitudinal study. On the other hand, this apple browning lab is only a simulated case of underdetermination that the problem can be easily avoided by using other means to cut off the oxygen instead of using ascorbic acid. However, from the perspectives of the students who do not know the roles of ascorbic acid, the experience of underdetermination is real.