Chapter 2 36 Reformed Liberated/Protestant),17 the size of the town (largest cities/big cities/smaller cities/villages) and the number of orthodox Protestants living in that town (few/many) were used. The last two criteria were added, as it could be assumed that the environment of the school influences how religious diversity is experienced within schools. The size of the town and the presence of orthodox Protestants could be seen as indications of the number of religious (and/or cultural) others in the region. The bigger the town and the smaller the presence of orthodox Protestants, the more likely the presence of religious (and/or cultural) others. There were a total of 166 OPPSs within 50 km of Utrecht. Selection procedure The combination of selection criteria lead to 18 different categories of schools. Each of the 166 OPPSs was classified into one of the categories (see Appendix II). If there were multiple schools from one town in the same category, they were randomly ordered. For each category the principal of the first school was contacted by email, providing some background information about the study, and there was a follow-up call within a week. I asked the principal whether the teacher of grade 518 or, alternatively, the teacher of grade 4 could participate in the study. Some principals gave me contact information to directly invite the teacher(s) myself. Other principals asked their colleagues whether they would participate, or decided that participation was not possible or desirable, mostly arguing that teacher workloads do not allow time for participation. When a first attempt did not lead to a participating teacher, the process was repeated by contacting the principal of the next school in the same category. Principals were not involved in any further communication with participants. I approached a total of 47 schools, 15 of which participated (31.9%positive responses19). Three of the identified categories could not be represented in the sample: I was not able to find teachers willing to participate from a Reformed Liberated primary school in a village or from a Protestant school in a city with few orthodox Protestants. Also, there are no Protestant schools in one of the largest cities, so instead a Protestant school of a big city was approached.20 Teachers who did not want to participate said that they weren’t interested in such an interview or did not have time for it. 17 Dutch: reformatorisch/gereformeerd (vrijgemaakt)/protestants-christelijk 18 In the Netherlands the 5th grade is the penultimate year of primary school. 19 In Chapters 4 and 5 a percentage of 38.5% instead of 31.9% was mistakenly mentioned, because it counted 39 instead of 47 approached schools. 20 The fact that this school is officially registered as Reformed and not Protestant was missed, and that only turned out after conducting the interviews. Remarkably, the participants also spoke about the school as being Protestant. The school was kept in the sample because this was not expected to influence the outcomes negatively.