No child under the age of sixteen (16) years shall be employed, permitted, or suffered to work for more than six (6) days in any week, nor more than forty-eight (48) hours in any week, nor more than eight (8) hours in any day or before 6:00 a.m. or after 7:00 p.m., except that on nights preceding nonschool days, children under the age of sixteen (16) years may be employed until 9:00 p.m.