CRANBERRY TWP — The fate of the historic one-room Johnston School has been sealed. A last-ditch effort to save the school last month did not produce any viable ways to keep the building. Cranberry officials have determined that restoring the one-room Johnston schoolhouse on Mars-Crider Road is not a practical option for the decaying 162-year old building. Because of that, the building will be torn down starting Monday. However, some of its bricks will be saved and reused in the Cranberry’s new Kids Castle playground to be built this year in Community Park off Route 19. John Trant, Cranberry’s chief strategic planner, said options to save the building were explored. “It’s become a liability issue,” he said. “We would have liked to save it. But, with the reluctant blessing of the historical society, we’re going ahead with the demolition.” For nearly 40 years after the Southwest Butler School District was formed in the early 1950s, the 1851 Johnston School house building, one of six one-room schools which had previously operated in Cranberry, was used as a private residence. Following its abandonment 15 years ago, the building fell into disrepair. The Johnston School is behind Target and the Cranberry Commons mall.