The attendance supervisor shall, upon receiving the list of nonattending children from the county superintendent of education, contact as rapidly as possible the parents or guardians of such nonattending children with the object in mind of interesting nonattending children in school work, and influencing them by means of persuasion to attend school regularly. All principals shall report to such attendance supervisor on continuous absences which appear to be unwarranted, and the attendance supervisor shall make an earnest effort to have enrolled and keep enrolled all children of school age in the county.