Current affairs knowledge of Olympian heroes has never been so precious for 17-year-old Lau Yu Han.

On Wednesday, the Year 5 NUS High School of Mathematics and Science student correctly named Michael Phelps as the swimmer that had eight gold medal wins at the 2008 Beijing Olympics and held 39 world records.

That was the tiebreaker question to determine whether it was his school or Dunman High School which would progress from the quarter-finals of The Straits Times-Ministry of Education National Current Affairs Quiz, or The Big Quiz.

A relieved Yu Han said after the Quiz: "We were lucky."

His school was among six - from 18 pre-university institutions in the quarter-finals - that emerged victorious at Wednesday's showdown at the Singapore Press Holdings News Centre Auditorium in Toa Payoh North.

The other schools that booked a place in the semi-finals are:

• Hwa Chong Institution
• Pioneer Junior College
• Anglo-Chinese Junior College
• Raffles Institution
• River Valley High School

Each school sent a team of three students and one reserve. Three teams competed against one another over two rounds; the winner of each group was guaranteed a semi-final place.

In the "Think Fast" round, each school had two minutes to attempt up to 30 questions. One correct question brought 10 points.

In the "Buzz In" round, each group of three schools competed among themselves to answer 30 questions. One correct answer earned 10 points; 10 points were deducted for a mistake or non-answer.