Looking to snag eight straight As for her upcoming A-level examination, Raffles Institution (RI) student Jenny Goh, 17, paid more than $800 for last-minute cram sessions during the June holidays for two subjects that she was weaker in.
She attended "crash courses" in physics and economics at tuition centre Quintessential Education Centre. Each course comprised two four-hour sessions, in which she brushed up on concepts likely to appear in the exams and crafted answers that examiners look for.
"I thought it would be good to clarify my doubts and get an idea of the key topics that will be tested," said Jenny, who hopes to study natural sciences at the University of Cambridge or Imperial College London.
The Year 6 student at RI, who previously scored U (unclassified) and E for economics and physics respectively, started doing better, and now averages Bs and Cs for the subjects. But Jenny feels that she can attain As when the written papers for the A levels start later this month.
These cram sessions are growing in popularity, with more teenagers signing up for them ahead of the N-, O- and A-level examinations.
Many students realise what they lack only when they revise just before the exams, and find that these courses can complement their own revision.
MR SHAUN LIM, Quintessential Education Centre tutor
Hundreds of secondary school and junior college students have attended such courses, which may last from a day to a few months, believing that these will boost their grades at the national exams.
At least 30 such courses have been or are being conducted this year. While some are held during the school holidays, others take place just days before students sit their exams.
These hothousing sessions - in the form of workshops or seminars - are designed to help students build up their confidence, clarify their doubts and spot questions likely to appear in the national exams.
Some tuition centres that offer such courses said their intakes have risen by at least 10 per cent from last year. A few are oversubscribed and have waiting lists of up to 15 students each.
Fees range from $180 to $900, depending on the duration and level of study. These courses cater for between 10 and 150 students.
The intake for Quintessential Education Centre's short courses for various O- and A-level subjects, such as chemistry and general paper, has risen by 60 per cent from last year, said tutor Shaun Lim.
It has offered three-day courses, which are held during school breaks, since 2013.
It is looking at opening up more places for popular subjects that are oversubscribed, such as economics.
"Many students realise what they lack only when they revise just before the exams, and find that these courses can complement their own revision," said Mr Lim, 32, adding that some students' grades jumped from E to A after the courses.
Tuition centres, such as Winners Education Centre and Potter's Clay Education Centre, have also noted improvements in their students' grades after the short courses.
But, said Mr Joel Liu, 29, owner of Bright Culture Tuition Centre, taking such courses does not guarantee an A grade, especially for weaker students, due to insufficient time.
Introduced this year, its two-session chemistry preparation courses for the O levels and A levels reinforce key formulas and expose students to likely exam questions. The courses in the June and September holidays were oversubscribed.
"Some students might not have the time for tuition during the usual school term, and choose to cram as much as possible during the school holidays," said Mr Liu.
Economics tutor Anthony Fok, 32, has been conducting his four-session intensive revision programme - which costs about $700 - every October since 2013.
This month's course, which will take in 150 students, already has a waiting list of 15 students. Mr Fok will help students spot topics for the A-level economics paper by analysing past years' trends.
He said: "Students know such tips are valuable. It helps them narrow down the scope of topics to focus on, especially when exams are nearing. But, of course, I always remind them not to take any chances."
Students said such courses allow them to catch up with their peers.
Mohamed Shahfizan Fazil, a Secondary 5 student at Ahmad Ibrahim Secondary School, admitted that he lacked self-discipline to study on his own and needed an "extra boost".
The 17-year-old, who is sitting his O levels this year, attended a five-day mathematics course at EduFirst Learning Centre during the September school break. He noted that it helped him to clear up common misconceptions.
Experts noted that such courses, while beneficial for students who need extra coaching or have low confidence, may not have much effect on those who are already putting in their best. Some even warned that they may be counter-productive.
Associate Professor Caroline Koh, deputy head of the psychological studies department at the National Institute of Education, explained: "Crash courses may be detrimental to learners who are already working flat out, especially when they offer nothing more than drill and practice sessions without the provision of feedback customised for individual learners."