I am doing my Master's dissertation linking some grade 6 science teachers' qualities with their students', quantitatively, in certain private schools in my country; they are following some organization.
This organization has schools in different regions of the country, but mostly in the North. That's why I chose all North schools to conduct my study in (they are nine). I chose all grade 6 science teachers in these schools, because their number is only 14, to be in my teachers' sample, and I took all their students as my students' sample.
My supervisor and readers were happy with the work, but they told me I should mention the name of the sampling method and that it might be "convenience sampling". However, I cannot see its suitability here, since I chose the North region not because it is convenient to me, but because it has high number of schools.
What might be the best sampling method in your opinion?