"I think my attitude wasn't good at the start," he says. "I was thinking about how I was going to spend my vacation there, asking for a comfortable place to live, in a good location, and so on."
Lu found a volunteer position through AIESEC, the world's largest student-run organization, and after passing an interview with teachers from the University of Nairobi, he was offered a position teaching at St. Catherine School.
"It's a potentially dangerous place to work as there is a pretty high rate of robbery and a high incidence of AIDS in the slum, but I convinced myself that this was an opportunity that might only happen once in a lifetime," he says.
The school was on the edge of the slum, which made it a safer place to work, and Lu lived with five other volunteers from Norway and Russia.
Each room in the school Lu worked at was divided by short partitions into several classes.
"Sometimes I had to find a way to help my students concentrate while another group in the room was having a class at the same time," he says.
Lu taught "creativity", which included painting, Chinese military boxing and debating.
"This subject was actually created by me as a way to broaden the children's minds with something that could not be learned in textbooks," Lu says.
During debates he encouraged the 18 students in his class to give their opinions on what it means to be good or bad.
During weekends Lu also helped out at a home for orphans, where hugs were the most valuable thing he could offer. On one occasion, he held each child up to touch the top of some goalposts at the school, which is the only entertainment they have.
"They were different from the children at St. Catherine, because they didn't have parents and you could see the sadness in their eyes," Lu says.
Lu played hide and seek with the children, taught them to count in Chinese and told stories. By the time he left, he says, he had developed a deep affection for them.
"I wish I could see them again. I would like to know how things are going for them in a few years."
On his last day in Kenya, after 35 days as a volunteer, Lu spoke with his landlord about the experience.
"I told him that I felt like I had done nothing to change the situation, as nothing was different after 35 days. It was just like a small wind had gone by," he says.
"But I was impressed by what he told me: that even small things matter."
When a student at St. Catherine asked him when he would return, Lu burst into tears.
"I will go back in five to 10 years. I definitely want to see those children again," he says.
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