The State Board of Education shall designate a uniform series of textbooks which shall be used in every free public school of this State receiving any State aid for any purpose whatsoever. No school failing or refusing to use such uniform series of textbooks, unless expressly permitted by law so to do, shall receive any State school aid for any purpose whatsoever. But the provisions of this section shall not apply to any school district that provides free schoolbooks to the value of twenty thousand dollars or more to the school children of such district. The State Board of Education is hereby charged with the enforcement of this section.