"My friend probably told me because she felt uncomfortable approaching an adult," she recalls.
This is when the primary school student decided to confront the bullies.
"I spoke to the girl who teased my friend the most. I did not shout at her, I was polite but firm. When I talked to her about how she had been making my friend feel she was shocked and didn't have anything to say.
"I don't think even she realised that she was being very mean. No one really intentionally wants to be bad."
This was six years ago.
Today Emma, a top-performing student at Westlake Girls High School, is set to attend an international leadership summit for teenage girls being held at her school.
She is one of 92 girls nationally attending the two-day programme being hosted by The Alliance of Girls' Schools Australasia.
The non-profit organisation aims to encourage young women to become champions of social justice and equality.
Executive officer Loren Bridge said the teenagers had true initiative. This year the theme focused on how to bring about social change in the community.
Westlake Girls High School principal Roz Mexted said it was a privilege to host the conference and support the development of young female leaders.
Writer and human rights activist Marianne Elliot is a keynote speaker.
She said teenage years were the best time to cultivate social awareness and leadership skills.
"It is a time when you have a future-focused perspective. You are not caught up in the status quo. If you don't feel something is right, you are ready to work towards making things radically different."
Other prominent speakers include award-winning activist Shruthi Vijayakumar and Laura O'Connell-Rapira - the campaign director at ActionStation, events director for Our Place Events and the co-founder of RockEnrol.
Girls for Change
What: Girls for Change Leadership Summit: Making a Difference.
When: The two-day programme starts today at Westlake Girls High School.