Ock Mi-eun, 57, has been taking care of her grandson since he was born two years ago so that her daughter could return to work. She receives 1 million won ($830) a month for her services.
It is not unusual for South Koreans to pay their parents to take care of their children. But the number doing so is on the rise and the arrangement has become more professional-like as parents increasingly pay the equivalent of full babysitting rates.
"You've left your child with someone else, it's only being responsible to pay some compensation," said Ock, who picks up her grandson from his morning daycare and looks after him until his mother retrieves him in the evenings.
Childcare classes for the elderly, rare before 2013, have cropped up at public health centers. They typically teach the resuscitation technique CPR, infant massage, feeding and playing with children.
"They're very eager to learn modern-day childcare because so much has changed from their time, and they don't want to be looked down on by their children," said Song Geum-re, who lectures at childcare classes for the elderly.
The trend is being driven by changes in South Korea's population - the fastest-ageing in the world. A record share of women work and a high rate of poverty among the elderly means many older people need the income.
Even though government data shows almost 53 percent of women work, that level is low compared with other member countries in the Organisation for Economic Co-operation and Development.
As of April 2014, 22.4 percent of all married women aged 15 to 54 in South Korea had quit their jobs due to marriage, childbirth or childcare, government data shows.
New mothers are often deterred from returning to work by a lack of day care, where demand far outstrips available places. A ruling party lawmaker said last year there were 11 children for every day care spot available and in the more sought-after government facilities the ratio was 47 to one.
An instructor gives a lecture during a child care class for grandparents in Seoul, South Korea, September 1, 2015.
The share of families whose children were looked after by grandparents rose to 35.1 percent in 2012, the last year for which government data is available, from 31.9 percent in 2009.
A survey by the Gyeonggido Family and Women's Research Institute in 2011 showed nearly 80 percent of 300 grandparents who regularly took care of their grandchildren were paid.
Suh Moon-hee, a visiting research fellow at the Korea Institute for Health and Social Affairs, said paying grandparents for childcare is not new but the prevalence and the amounts paid have risen, suggesting a more professional arrangement.
"In the past, if South Koreans paid a third of what they would have paid visiting babysitters because they regularly gave their parents financial support. Now they pay them full wages," she said. "It's more of a transaction for services."
For many families, enlisting grandparents to look after young children has mutual benefits.
Compensation for childcare can be a key source of income for elderly people in South Korea, where government data shows that 49 percent of those aged 66 and above live in poverty.
One Seoul district began paying monthly stipends in 2011 to grandparents who regularly take care of their young grandchildren. A lack of funding has derailed similar initiatives elsewhere.
The new professionalism among grandparent carers even shares some traits with daycare centers. Many grandparents are strict about working hours, Song said, with some cutting off service at 6 p.m. sharp.
"Grandparents exchange information amongst their friends, who's being given how much and whatnot. It's all business-like," she said.