(1) Summer school means educational opportunities that, except as otherwise provided in this section, are undertaken on a voluntary basis by students who will be entering any of grades one through twelve in the next school year and are offered during the period of time between two consecutive school years.

(2) Summer school may be offered by any school district.

(3) The board of education of any school district may require children between and including the ages of six and fifteen years, regularly enrolled within the system and deemed by the school administration to be making unsatisfactory progress, to attend summer school for up to one-half of a regular school day if in the opinion of the administration they would benefit from the experience. Chief emphasis in such summer classes shall be on reading, language arts, and arithmetic and those areas of personality development especially in need of development. Teachers shall be encouraged to design new and imaginative techniques and curricula not usually used during the regular school year which in the opinion of such teachers will offer new incentives towards learning, with special emphasis on those techniques that seek to develop the students’ personalities in a wholesome manner, especially developing pride, self-confidence, and self-control. Teachers of such classes shall not be assigned more than fifteen students, or more than twenty-five students if assisted full time by an aide or paraprofessional. Such students shall be graded at the end of the course upon their relative degree of striving to improve their skills, attitudes, and personalities.