Most of the 10,000 residents of Ambae have relocated to the islands of Maewo and Santo.
The NGO said that included about 2000 children but there were not enough schools available to accommodate them.
Its Vanuatu country director, Georgia Tacey, said so far the group had set up seven tents to provide child friendly spaces on the island of Maewo, where there were about 800 displaced children.
"We have a focus on keeping children safe and away from adult conversations so it's there to support their psychosocial recovery - not so much focusing on structured learning."
It was a frightening and disorientating time for many children, Ms Tacey said.
Photo source Linda Kalman/Facebook. Caption: children from Ambae who are now residing at the Sanma chiefs nakamal.