The board of education of any school district may authorize the establishment of a nonsectarian charter school as a means of providing new opportunities for:

(a) Improved pupil learning;

(b) increased learning opportunities for pupils in special areas of emphasis in accord with themes established for charter schools;

(c) creative and unconventional instructional techniques and structures;

(d) new professional vistas for teachers who operate such schools or who choose to work in them; and

(e) freedom from conventional program constraints and mandates.