Reflection on the study

The CoRe helped to portray how the teachers conceptualised the teaching of radioactivity and the PaP-eRs made the tacit knowledge of teaching this topic explicit because of the narration of the teaching process that they illuminated. Through the use of these instruments, it was possible to compare and contrast the PCK of these teachers.

I adapted the method of Loughran et al. (2004) for capturing, portraying and documenting the two teachers‟ PCK. Unlike Loughran et al. whose CoRes were constructed by number of

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experienced science teachers working together to come up with the big ideas around the topics they were working on, this study involved only two teachers; one experienced and another a beginning teacher. I constructed the CoRe using data gathered through interviews and class observations. I inferred the big ideas in the topic of radioactivity looking at what the teachers viewed as important in helping to understand this topic as a whole. The big ideas shed light on how the teachers framed this topic. I did not allow the two teachers to come up with big ideas they agreed upon as Loughran et al. (2004) did because in this study I was interested in these teachers‟ similarities and differences in their PCK so their agreement on big ideas would not yield results that would allow me differentiate the way they conceptualised PCK on teaching radioactivity. The CoRe allowed me to capture and record what each teacher denoted as aspects of PCK. I have constructed the CoRe such that the two teachers‟ responses are placed in the same CoRe for easy comparison so that similarities and differences can easily be seen. CoRe and PaP-eRs brought to light the links between knowledge of content and teaching contexts of the two teachers in this study. The CoRe and PaP-eRs also helped to portray the holistic overviews of the teachers‟ PCK related to the teaching of radioactivity that can be accessed by both experienced and novice teachers to develop their PCK.

There was one question in the interview schedule which one teacher did not understand. The misunderstanding was on the following question: what specific strategies would you use to ascertain student's conceptions or misconceptions of these ideas? I had to explain the question using simpler words to help the teacher understand. This suggested that the interview questions should be written in more simple English especially when the interview is done to people who speak English as a second language. Another possibility would be to rephrase the question in Sesotho. However an advantage of the interview situation is that it is possible to rephrase the question immediately and clarify. The questions I used in the interview were in fact the prompts of the CoRe. If I could have just given these teachers the CoRe to complete, then the teacher who did not understand one question could have been stuck and I could have not got the response I was looking for and lost important data which could have negatively affected the results of the study.

The diagnostic test served to access the teachers‟ subject matter knowledge. Question 4 of the diagnostic test only required that teachers should use their basic knowledge of calculations on half-life but since teachers are expected to know more than they teach (Bishop & Denley, 2007), I should have added a question that would require teachers to use their deeper knowledge on calculations. For example, I could have asked a question that asked about the remaining mass

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after 600 days of a radioactive substance of 1g, with a half-life of 20 days so that I could see if the teachers were able to solve the problem using methods other than a step by step calculation such as a formula. This would have determined if they had deeper subject matter knowledge. These two teachers used successive halving to solve this question, which is the method they used in their classroom practice and the method does not suggest whether the teacher had a deeper knowledge on this concept or not but Mr Victor showed that he possessed the knowledge of using the half-life equation.

The model of Rollnick et al. (2008) has helped me to describe the teachers‟ manifestations in their classroom practice and their opinions about teaching radioactivity from interviews and post observation discussions. The way these teachers considered some or all of the four knowledge domains was exhibited in their way of teaching radioactivity. This model helped to show the well developed PCK when the teacher had integrated the four knowledge domains and the poorly developed PCK when one or more of the knowledge domains were not considered. This model has also helped in relating classroom practice to domains of knowledge that generated such practices.

In the first day of video recorded classroom observations, the two teachers felt insecure due to my presences in their classroom even though they had allowed me to observe them. I had to re- establish the issue of trust between us by reminding them of the aim of my study that I wanted to learn from them not to judge the way they teach. This issue of insecurity could have made these teachers change their behaviour (Descombe, 2007) and I might have lost the some of the important data such as flexibility in the teaching strategies that a comfortable teacher could have displayed that would enrich their portrayed PCK. Although video records served to access the teaching process, some of the words could not be heard from the video records and the voice recorders that I used helped me to get the inaudible words but they too failed at times and the words could not be heard which contributed to the lost data.