The Missouri Board of Education voted Tuesday to extend its oversight of the Riverview Gardens school district until June 2016. The district of 6,000 students in northern St. Louis lost accreditation in 2007 because of its continued low test scores and has since been controlled by a three-member, state-appointed board. The district is looking for a new superintendent and the move will help provide clear expectations for prospective candidates, Education Commissioner Chris Nicastro said.