Things said online are instant, public, viral and permanent, the man behind Singapore's kindness drive told about 400 children gathered at the School of Science and Technology at Commonwealth Avenue West on Wednesday.

"Once you click on the button, you can't take it back," said Dr William Wan, general secretary of the Singapore Kindness Movement, at an annual cyber wellness conference held by the Education Ministry to spread awareness about good online practices amongst students.

He warned the pupils - ambassadors of cyber wellness in their schools - that one's behaviour online "may even affect the people we love". He was referring in particular to the case of Briton Anton Casey, who was flamed online after making disparaging comments about public transport commuters in Singapore. His young son was also targeted by online attacks.

Dr Wan also cited the example of former NTUC employee Amy Cheong to highlight the importance of responsible online behaviour. Ms Cheong had drawn flak from netizens and later lost her job, after making insensitive comments about Malay weddings.

Besides Dr Wan's sharing session, the conference also saw 10 schools being recognised for their efforts in promoting cyber wellness.

One of these schools is Anderson Primary.

The school got its Pri 5 pupils to learn about things like online etiquette and online copyright issues by getting them to design comic strips.

"By getting the pupils to show the different areas of cyber wellness in the comic strips, they get to learn from it too," said Rudraksh Pillai, a Pri 6 pupil who came up with the idea along with fellow Pri 6 pupil Dion Soh.

The School of Science and Technology will host another cyber wellness conference on March 26, for secondary school students. The conference for junior college students will be held on March 17 at Innova Junior College at Woodlands.