"I felt the calling. I can't do much on my own, but it's a starting point, which I believe will make a difference one day," Zhou says.

Her belief echoes Dashan Xiaoai's slogan: "The smallest act of kindness is worth more than the grandest intention".

Cao Yiming, who was a volunteer teacher in 2013, says that the students showed him a touching degree of warmth.

"Unlike the hustle and bustle of city life, life in the countryside is fulfilling, and joy is found in the simpler things in life," Cao says, adding that when he came down with a sore throat, a student who wasn't in his class brought him honeysuckle to soothe the pain.