SEOUL, Aug. 5 -- A growing trend among South Korean elementary schoolchildren involves dating for just a single 40-minute class period to avoid being labelled "mosol," or "single since birth."

Singer Jang Yoon-jeong recently shared her surprise after learning from her children about "one-period couples," who start and end relationships during school recess, according to a report in The Korea Herald.

"You just give a note to a friend you like, saying, 'Do you want to go out with me?' and if he says yes, then we are girlfriends and boyfriends. Then we break up after the class ends," said an 11-year-old student surnamed Kim.

"When my son explained this culture to me, I was stunned," said 45-year-old Kim Joong-whan. "'Is this some kind of ...