MYRTLE BEACH â As thousands in Horry County and across South Carolina reconsider their format of school instruction before the second semester, medical experts are casting a wide net in questioning the effectiveness of plexiglass used as dividers in classrooms, calling the measure a âplaceboâ and pointing to the lack of data to determine the true impact. In mid-November, the Horry County Schools Board of Education unanimously voted to use nearly $5 million in state funds to install plexiglass throughout the district to try and combat the spread of COVID-19 in classrooms, something already complete in many other South Carolina school districts.