To allay teacher concerns that assessments will be tainted by personality clashes with principals, IMPACT will employ a corps of third-party "master educators" to conduct two of the classroom observations. The District's old system, like those in most other cities, required fewer classroom visits and left them largely to school administrators, who often had neither the time nor the expertise in subject matter to render fair evaluations, educators say. The master educators, who do not report to the principals, have backgrounds in the teachers' subjects.