Sample and sampling techniques

“The quality of a piece of research not only stands or falls by the appropriateness of methodology and instrumentation but also by the suitability of the sampling strategy that has been adopted” (Pillay, 2006, p. 50).

This extract suggests that one of the key elements of an effective case study research method is the adoption of a suitable sampling strategy that ensures the selection of appropriate participants to generate rich data cases. For that reason, care was taken when doing sampling for this study. As Cohen et al. (2007) point out, sampling in qualitative research is often deliberate, usually bearing specific criteria in mind and choosing specific cases which are best suited to the needs of the researcher. Merriam (1988, p. 61) emphasises that “purposeful sampling is based on the assumption that the researcher wants to discover, understand and gain insights into and therefore must select a sample from which the most can be learned”. Hence, in this study, I employed a purposive or purposeful sampling method/technique (Creswell, 2007) to identify appropriate teachers from different schools in different education regions. This enabled me to generate meaningful and relevant data to support my findings.

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The study was conducted with five purposively selected teachers from five different schools. The National Institute of Educational Department (NIED) staff in Okahandja, Ministry of Education (MoE) officials at the Head office in Windhoek and staff in the Faculty of Education (FoE) at the University of Namibia (UNAM) as well as Regional Education Mathematics Advisory teachers were approached for assistance in identifying possible “effective mathematics teachers” to take part in this study. Although I only needed five teachers, I requested the MoE and UNAM officials to identify 10 teachers, from whom I selected five.

Sampling was carried out in two stages:

 In the first stage, I approached and engaged the Ministry of Education personnel to select 10 teachers in Namibia who have consistently achieved the top results in the Grade 10 and 12 national examinations over the last three years. Archived statistical information (examination results) on Junior Secondary Certificate (JSC/grade 10) and Namibian Senior Secondary Certificate (NSSC/grade 12) students’ performance in mathematics over a period of three years was used in selecting 10 teachers/schools.

 The second stage involved contacting these 10 identified teachers and inviting five volunteers to participate in my study. The study objective was clearly articulated and I emphasised that the ultimate objective of this study was not to evaluate their teaching and compliance with the curriculum but to analyse factors that contribute to their effective teaching practice. After giving out copies of the information sheet to the teachers (see Appendix C), they were asked to decide whether or not they would like to be a part of the study.

Certain criteria had to be met in selecting the final participating teachers from the list of contacted teachers. The prime selection criteria used were:

 voluntary participation and willingness to share teaching practices and experiences;

 mathematically qualified secondary school (Grade 8 to 12) mathematics teachers, namely, those who have a minimum Basic Teacher Education Diploma (BETD) teaching qualification;

 high performing teachers in terms of learners’ mathematics performance who have a high standing and ‘good reputation’ in the mathematics education community of practice as determined by their significant peers, and

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 the participating teacher and school had to be committed to the project for the entire duration of the project.

The teachers come from high schools in five different educational regions of Namibia. There are 13 educational regions in Namibia. The participants showed a high level of interest and enthusiasm.

3.3.2.1. Participants

My participants were two males and three females. Even though gender was not a central factor in this research, it is important to point out that the dominance of female mathematics teachers in my sample of participating teachers was neither purposive nor deliberate, and is not representative of mathematics teachers in Namibia. Table 3.1 below summarises information about the participating teachers. For the purpose of this study, the participants and schools have been categorised or coded as follows. Teacher 1 is referred to as Demis of school A, Teacher 2 as Jisa of school B, Teacher 3 as Ndara of school C, Teacher 4 as Emmis of school D and Teacher 5 as Sann of school E. I used pseudonyms in order to protect the participants in terms of privacy, confidentiality and anonymity. However, as Lankshear and Knobel (2004) suggest “assuring confidentiality and anonymity is actually quite difficult to put into practice as some schools are readily identifiable because they are easily recognised in the region” as they performed well (p. 110).

Table 3.1: School type and teachers' demographic information in my sample

As the age distribution in the table above shows, two of the five teachers were forty years old or older, and three of them were over thirty years old. The table further shows that four (80%) of the teachers in the sample had more than six years teaching experience. My sampled schools are spread across five regions in Namibia, namely, two (B and C) in the northern regions, two (A and D) in central regions and one (E) in the coastal regions.

School School type Teacher and Name

Sex Age Levels of study Teaching experience

in years

A Public T1: Demis Female > 40 Gr.12, BSc, HED 20

B Private T2: Jisa Female 30-40 Gr.12,B.Sc, MSc, BEd 10

C Public T3: Ndara Male 30-40 Gr. 12, B. Science 6

D Private/Day T4: Emmis Male > 40 Gr. 12, BEd, MEd 15

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