A 7-year-old girl returned to Forwood Elementary School on Wednesday, three days she was pummeled by a fifth-grade student in an attack on their school bus, an incident caught on video on another student’s cell phone. The assault, which is being investigated both by Brandywine School District officials and state police, has prompted some changes to ensure students are safe when riding the bus to and from school, district Superintendent Mark Holodick said.