When Lee Hong Qi, 17, received her O-level results last year, she knew it was not her best performance.
She obtained an L1R4 score of 16 points - for English and four relevant subjects - which meant she qualified for only the polytechnics.
"I didn't want to go to a polytechnic because I didn't know what course I wanted to do, and I preferred JC (junior college) as it's the common route to enter university," said the daughter of an engineer and a housewife, who has two younger brothers.
So she decided to re-sit exams for four subjects - additional mathematics, elementary maths, English and combined science - and signed up at private school Penciltutor.
She said: "I studied 10 times harder, cut down on going out with friends, and learnt from my mistakes. I came up with study schedules so I could do sufficient revision before the exams, unlike previous times, when I didn't do enough preparation.
"I was very playful before, and I usually ended up among the bottom half of the cohort in school."
Her classes at the school in Jurong West, which started in March and took place four times a week, cost $3,150. She eventually scored A1s for all subjects except English, for which she got a B3. Her biggest improvement was going from a C6 grade to A1 for A maths.
This time, her L1R5 score - based on results for English and five relevant subjects - was 13 points, which meant she qualified for JC.
To enter a JC, a student's L1R5 score must not exceed 20 points.
Hong Qi, who hopes to go to Jurong JC, which is near her home, said: "The small class sizes at Penciltutor really helped as the teachers could pay more attention to me... With my previous score, I felt quite lost because I couldn't get into JC."