"Many suicides - particularly those of children - are preventable," NZAC spokeswoman Sarah Maindonald said.
"Counselling and robust pastoral care systems in primary, intermediate and secondary schools can identify signs of psychological distress, depression and other risk factors which may signal a need for further intervention.
"This is no judgment on any school or family - as suicide can be an impulsive decision - but one we must come to grips with as a nation so we can make systematic changes.''
Neither of the girls' families have spoken publicly about their ordeals.
However, the Ministry of Education said its staff had been in close contact and helping to support Massey Primary School's staff and student community, where the 10-year-old girl attended.
Maindonald, who is a school guidance counsellor, said there was a need to raise awareness of the benefits of having such counsellors in schools and knowing how to tap into their resources and services to help children.
There was no shame in talking about emotions, she said, as talking about issues was often life-saving.
"We need well-resourced student support services like school counsellors, but we're missing a step,'' she said.
"Children and teenagers don't naturally refer themselves to mental health services.
"They often need a bridge - they need someone like a school counsellor who can follow up with the right questions.''
Where to get help:
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• Samaritans: 0800 726 666
• If it is an emergency and you feel like you or someone else is at risk, call 111