Tennessee Code Title 6. Cities and Towns § 6-36-101

(a)(1) If a city incorporated under this charter is authorized, pursuant to general law, to establish and operate a school system, the control and management of the schools of the city shall be the responsibility of the board of education, which shall consist of five (5) qualified voters of the city, meeting the requirements of §§ 6-31-105 and 6-31-112.

(2) By ordinance adopted by a two-thirds ( 2/3 ) vote of the entire membership of the city council, the board of education may be increased to seven (7) qualified voters of the city, meeting the requirements of §§ 6-31-105 and 6-31-112. The two (2) additional board members authorized by this subdivision (a)(2) shall be elected at-large and shall be voted on by the electors in all voting precincts of the city. This subdivision (a)(2) shall only apply within counties having a population of not less than thirty-one thousand five hundred (31,500) nor more than thirty-one thousand eight hundred (31,800), according to the 1990 federal census or any subsequent federal census.