A teenager who stole a classmate's belongings in a scam involving two other youngsters - during which one played the 'robber' while the other two acted as 'victims' to make the theft appear more convincing - was sentenced to a spell in a detention centre yesterday. Tang Wing-fai, 17, helped steal a mobile phone and PlayStation Portable from a classmate at a park in October last year. He had earlier pleaded guilty to conspiracy to rob. Passing sentence in the District Court, Judge Joseph Yau Chi-lap said it was a pity to see a student commit such an offence because of material temptation. Tang's two 15-year-old co-defendants pleaded guilty to the same charge. One was sentenced to a rehabilitation centre, while the other is awaiting sentence. Prosecutor Jones Tsui said Tang and one of the co-defendants attended the same school as the victim, while the other had dropped out of school. The crime happened at about 3pm on October 3, when the victim, Tang and one co-defendant were on their way to Kwai Hing MTR station. Tang proposed a shortcut, and when they arrived at a park near their school, the second co-defendant confronted them as the 'robber'. As part of the act, the youth punched Tang in the chest and threatened him with a knife. Then the 'victims' were taken to a car park in Kwai Hing and forced to give up their phones. The genuine victim was also forced to hand over his PlayStation. The case came to light when the genuine victim saw the other two using their 'stolen' phones at school the next day. The robber was arrested and told police he sold the articles for HK$1,530, with the money divided among the three. Judge Yau said the plan was premeditated and well-planned, as shown by the fact that Tang was punched in his chest in order not to arouse the victim's suspicions. The court was told that Tang's father was a drug addict and behaved irresponsibly towards his family. His mother was busy working to support the family, and therefore gave little parental care to her two sons. Tang's younger brother was sentenced to a drug treatment centre earlier this month. Judge Yau added that Tang's case provided an opportunity for society to reflect on whether such families received enough help under the social welfare system. He also noted that sending Tang to a detention centre was appropriate, as it was more important to help him get back on the right track than to simply punish him.