The Jefferson County Public School Board will replace up to half the teaching staff at three high schools with low test scores. At its meeting last night, the board voted 5-2 for the option.Superintendent Sheldon Berman recommended restaffing for Iroquois, Southern and Waggener high schools, telling the board it will be the least disruptive. The board chose restaffing over an alternative that would have linked teacher evaluation and pay to academic performance. All the teachers who are replaced are guaranteed another job in the district.The state designated the three schools as “persistently low achieving” last year because of low reading and math scores.