A teacher who mercilessly beat up a six-year-old student in a public school here was arrested Sunday, police said. Police registered a case against the teacher under the Juvenile Justice Act.The action came a day after Rekha Singh, the mother of the child, alleged that police have registered a weak case on charges of voluntarily causing hurt."The teacher was arrested," said Inspector Arun Kumar of Vijay Nagar police station.Rekha Singh, a resident of Pratap Vihar area, said police have refused to book the guilty woman teacher under the Juvenile Justice Act. She said after returning from school at 2 p.m. Saturday, her son, a student of lower kindergarten class, was under severe shock and pain, said he was beaten by his teacher.The school is reportedly owned by a Samajwadi Party leader.