"They wanted to see what the donations did, and they sang us a few Christmas songs as well," she said.
"For children obviously it's often about what they're going to get. But to allow them to see how their kindness will help another child is incredible."
Sawyer said the children's teacher had felt it was important for the children to make the donation in person, rather the City Mission picking it up.
"She really wanted them to connect how their can of food or their present would go to another child," Sawyer said.
"That's how we grow amazing adults and an amazing community."
Teacher Jin Lu said the concept of donating to those in need was "quite abstract" for the children.
"But I think it gives them the idea of it, to try and give away something."
The visit came as City Mission staff finalised preparations for their annual Christmas lunch, which is the largest in New Zealand.
Auckland City Missioner Chris Farrelly said the lunch took several months of planning, hundreds of volunteer hours, and an "incredible display of generosity" from the wider community.
This year, the menu included the preparation of 2000 chicken drumsticks, 300kg of ham and 540kg of vegetables, and bucketloads of jelly.
Since the beginning of December, the City Mission has given out emergency food parcels to 350 families every day, and donated at least 7000 gifts.
Doors to the Christmas lunch, at the Viaduct Events Centre, open at 11.30am on Sunday.