This story is part of a nationwide Patch series probing the economy's effect on local schools. While school districts across the state and country have trimmed teaching staff and ballooned class sizes to cope with tight budgets, Reading's public school district has weathered the turmoil with only limited cuts. Superintendent John Doherty said, in the last two years, the district has cut only two teaching positions, and those would have been eliminated even in better fiscal times. This year's fifth-grade class is smaller than those in the past, he said, which allowed the district to function …