Ley Hathcock, who is a former engineer and has been with Hall County Schools since 2011, will be the interim principal at Martin Technology Academy of Math and Science. He will replace Tamara Etterling, who is the new principal at North Hall Middle School. “His unique background which includes teaching, school-level administration, leading our district technology crowd-sourcing initiative and extensive work owning a private sector engineering firm make him an ideal choice to lead MTA forward as they seek to become fully STEM certified,” Will Schofield, Hall County superintendent, wrote Friday in an email announcement.