The State Board of Education shall adopt measurable academic content standards for at least the grade levels required for statewide assessment pursuant to section 79-760.03. The standards shall cover the subject areas of reading, writing, mathematics, science, and social studies. The standards adopted shall be sufficiently clear and measurable to be used for testing student performance with respect to mastery of the content described in the state standards. The State Board of Education shall develop a plan to review and update standards for each subject area every seven years. The state board plan shall include a review of commonly accepted standards adopted by school districts.