After the first series went viral online, Chen Zhuo explained that it was Yu's 30 years of teaching experience that inspired him.

Her husband died from pancreatic cancer about 20 years ago, but she has remained passionate and curious about life.

Before living in the care home, Yu spent six years at a university for the elderly. As she came to the age when she needed more healthcare services, the then 81-year-old decided to move into a nursing home.

"But her life became less active in the care facility, until we started filming. Since then, she has been learning about filming techniques and participating in editing scripts. She told me later that life is fun when you learn, no matter what age you are," Chen Zhuo says.

Following the success of the chemistry lesson series, he has created other popular videos, including the series, Inspirational Wisdom and Sensibility and At the Nursing Home in 50 Years.

Chen Zhuo says he has learned a lot from the elderly during this process.

"They have faced grief and losses, including illnesses, family changes and the deaths of loved ones and friends. Life is so full of suffering, but no matter what it throws at them, they don't give up."

In the videos, Chen Zhuo tries to discuss aging and death in a lighthearted way.

In one video, for instance, Yu checks her contacts book to cross out the phone numbers of people who've passed away. As the ratio of survivors diminishes over time, Bob says the notebook is more like a "list of the living and the dead".Upon hearing this, Alice throws her phone away to avoid being listed.

A netizen with the online name "Yueliang" comments that, although death is a serious topic, she can't help but laugh when Alice throws away her phone.

"Aging and dying are inevitable," Chen Zhuo says. "I feel the resilience of these elderly people in the face of this natural process."

Contact the writer at wangqian@chinadaily.com.cn