Shuqun Secondary School has investigated a case of alleged bullying that took place in one of its classrooms last Friday and is counselling the students involved.
A 52-second video clip of the incident that has been viewed more than 315,000 times showed a boy from the school hitting two other boys on their heads repeatedly.
Both victims kept their heads bowed and did not retaliate. Another boy was seen dancing on the teacher's table in the background while the bullying went on.
The video, which appears to have been filmed by another student and was first posted on the Facebook page of citizen news site All Singapore Stuff yesterday, was also shared more than 9,800 times.
Replying to queries, the school in Jurong East said yesterday that the subject teacher who was supposed to be in class was on childcare leave. But it confirmed that an adjunct teacher who was present when the incident happened has since been spoken to.
The school added that the student "deeply regrets his actions".
"What might first begin as playfulness could potentially end up hurting others," a spokesman said.
"The school will continue to work with the students involved on observing appropriate boundaries and behaviour in the future."
The school did not elaborate on the actions it had taken but said the boys' parents had been informed.
Bullying is an often-repeated behaviour, physical or verbal, that involves aggression towards another.
The Straits Times understands that all the students in the video are classmates in the same Secondary 3 Normal (Technical) class.
A Secondary 3 Express student, who knows the ones involved but would not give his name, said: "They are just playing around but the slapping part is a bit extreme."
Parents said schools need to take action against bullying. Lawyer Edwin Lee, 47, a father of four boys aged 10 to 18, said: "This cannot be condoned anywhere, especially in a school. The boy must be sternly counselled and disciplined."
He added: "His fellow classmates who stood by silently should also be spoken to, to educate them that they should stand up for one another."
Dr Thomas Lee, medical director and consultant psychiatrist at The Resilienz Clinic, said: "School bullying is quite common and it's not rare for victims to keep quiet, for fear of making the situation worse."
He noted: "Sitting there quietly probably indicates that the boy has been bullied before. As you show more signs of being victimised, the bully gets bolder."
He said prolonged bullying could lead to long-term psychological trauma that could persist into adulthood.The presence of social media may deter people from behaving badly, "but I don't think it changes the bullying trend significantly".
Bullies act aggressively to show that they are in power, especially when they are surrounded by their peers, he said.
• Additional reporting by Lee Min Kok