A video of a girl wearing a big smile and a red coat recently went viral on Chinese social media.

Tie Jiaxin, a first grade student at Daping Elementary School in Xiji county of Guyuan, in the Ningxia Hui autonomous region, had just finished class and was waiting for the bus to go home. It was a little chilly outside.

The video was shot by Tie's teacher, Ma Rui, who thought she was cute and her smile healing.

"I thought the video was fun, so I uploaded it online," said Ma, who has taught music and mathematics at the school for more than a year.

"The kids here are so unsophisticated," she said. "Their smiles are innocent and confident."

Xiji had been one of Ningxia's poorest areas. In November last year, it was lifted out of poverty.

The smiles on kid's faces reflect their improving living standard and confidence in the future.