Pinellas County is adding two more charter schools to its growing roster. School Board members last week approved five-year charters for Plato Academy North in Palm Harbor and Plato Academy South in Largo, two new campuses expected to serve kindergarten through eighth grades. According to the agreement, both campuses will open to 144 students through third grade this fall, increasing through seventh grade in 2011-12 and through eighth grade in 2012-13. Plato Academy North will be located at 1601 Curlew Road in Palm Harbor and Plato Academy South will open at 7100 142nd Ave. N in Largo. The two are sister schools of Plato Academy in Clearwater, which opened in August 2004 and includes an emphasis on Greek language instruction among its daily lessons.