Hoping to give his son an edge in the Primary School Leaving Examination (PSLE) two years ago, civil servant Abdul Raziff, 48, paid more than $700 to put him through two study "boot camps".
The boy, then in St Gabriel's Primary School, attended intensive workshops in mathematics and science during the June holidays. Run by tuition school Edufront Learning Centre, each workshop lasted four days, with students put through their paces for three hours every day.
"I felt that he could gain from an extra push," said Mr Raziff.
His son Ali Azhari began doing better and eventually scored an outstanding 262 for the PSLE. Ali, 14, is now a Secondary 2 student at Raffles Institution.
Inspired by such stories, parents have begun signing up their children for such hothousing sessions in droves.
Hundreds of Primary 6 pupils, and some younger ones too, will be attending such cram sessions during this school break.
Education experts, however, warn parents that pushing their children too far can be counterproductive.
The one- to five-day boot camps, which take the form of workshops and seminars, are touted - and in some cases "guaranteed" - to lift their children's PSLE grades.
There are at least 15 such non-residential camps this month, and some can last up to nine hours a day - longer than the typical six-hour school day.
The camps are designed to help pupils clear up common misconceptions, focus on topics likely to appear in the national exam and craft answers that examiners are looking for.
In the past three years, most tuition centres which run these camps say they have upped their intake by at least 10 per cent. Fees range from $200 to $500, and they take in 20 to 500 pupils. A few have waiting lists.
Education centre Beautyful Minds' chief executive officer, Mr Neo Zhizhong, 32, has been conducting six-session PSLE preparatory courses every June since 2013.
This month's courses, which will take in 12 to 15 pupils each, are oversubscribed and have waiting lists of up to 30 pupils, he said, triple last year's number.
Science Alive Learning Centre teacher Hafiiz Rahman, 27, said this year's camp, where pupils get to revise topics via mind maps and handle experiments, has close to 40 sign-ups, up from 18 in 2013.
He warned, however, that "some parents are looking for a miracle, but these camps do not give instant results".
Mr Jerry Theseira, 37, owner of the EduGrove Mandarin Enrichment Centre, which runs a five-day PSLE preparation programme for Chinese, said: "We guarantee an improvement, but how much of an improvement still depends on the students themselves."
Some anxious parents have decided to get ahead by signing up their Primary 4 and 5 children.
Pre-school curriculum specialist Clare Ter, 30, for one, has enrolled her 11-year-old daughter, who is in Primary 5, for a three-day PSLE seminar for English, maths and science.
"It is better to give her more time to prepare," she said. "If she doesn't get the foundations right now, it would be tougher to catch up next year."
Overseas studies, however, have reported that time spent on these cram sessions, while good for the report card, had a negative impact on the pupils' psychological well-being.
Dr Timothy Chan, director of SIM Global Education's academic division, said putting unnecessary stress on pupils may lead to counterproductive outcomes, such as loss of interest in their studies.
He added that practice and reflection, which are important for in-depth learning, may be missing in these camps due to time constraints.
"The children have put in the effort during the school term. They should be rewarded with a break."