It is his sixth spell in prison and this time, he is determined to make it his last.
All because he heard his son screaming in the background as he was led away: "Ayah (Malay for dad), don't go!"
That scene, coupled with guilt and self-reproach, gave him the courage to change for the better.
"I made my children feel like orphans. Before I was jailed, I prioritised my friends over my family," said Ahmad, who has a nine-year-old son and a seven-year-old daughter.
"The day I walked into prison again, I told myself this can't go on. I have to turn my life around."
We are using a pseudonym to protect his family's identity.
Ahmad's N-level results, which he received on Dec 17, is evidence of his determination to change.
He scored 12 points, including three distinctions in Principles of Accounts, mathematics and Malay language.
"I'm grateful for my results but I wish I could have done better for my English," said Ahmad, who got a B4 for the subject.
The Tanah Merah Prison School student, who turned 40 recently, is serving a 5½-year sentence, which began in 2012, for drug-related offences.
His previous five jail terms were also for drug-related offences.
Ahmad said he had initially taken drugs to alleviate the stress from a failed marriage.
"But I relapsed on drugs and I started peddling. I knew that I would end up in prison the moment I relapsed but I just ignored those thoughts - until the day I was handcuffed right in front of my parents and kids," he said quietly.
His children are being cared for by his sisters.
Ahmad's time in prison became a period of self-reflection as he kept having flashbacks of how he was arrested in front of his loved ones.
"One day, my mum told me that my daughter quarrelled with my son and she shouted for me to come home," he said.
"When I heard that, I thought, 'Oh, man. I shouldn't be here any more'."
When the chance to do N levels came along, Ahmad jumped at it despite having not touched a book since primary school.
Inmates have to fulfil a list of criteria before they are eligible for studies. (See story above.)
Ahmad said: "When I was younger, I had this perception that education was just a waste of time and money.
"Now, as I am coasting towards middle age, with my hair receding and greying, I realise that education is very important, especially in Singapore.
"An opportunity was given to me, so why not grab it?"
The two years of compressed curriculum before he took his N levels were fraught with challenges for Ahmad.
"It was fast-paced and he had difficulty concentrating.
"I would be lying if I said I didn't feel like giving up," he said.
"But I just took a deep breath and told myself I must persevere.
"Whenever I'm down, I just look at photos of my kids and parents. They are my backbone."
Ahmad calls his time in prison "a blessing in disguise" because he was given the opportunity to study.
His thirst for knowledge shows in his frequent questions in class, an observation made by personal supervisor Muhd Hafiidz Abdul Aziz, 31.
A personal supervisor maintains order and discipline of inmates, and manages them by engaging them in purposeful and meaningful interactions.
"He's easier to deal with (as compared to other inmates). He's always studying and stays out of trouble," said Sergeant Hafiidz.
Thanks to the regimental lifestyle in prison, Ahmad found order in his life again - something he relishes.
"Daily activities are arranged for us. My life is made a routine by the regime here," he said.
"I used to go for days without sleep. Now, I sleep even before lights out," he added with a laugh.
Now that he has cleared his N levels, Ahmad is gearing up for O levels next year - something he likens to a war.
The thought of stepping out into society to look for a job once he is released is a tad daunting, but he is looking forward to it.
"I see that many companies are now willing to accept ex-offenders. When I apply for a job, they will ask me about my past and I can just declare (my jail terms)," he said.
"There's nothing to be afraid of. I'm a changed man now."
'I was disappointed when he got arrested again'
Two years ago, he watched as police officers handcuffed his father and led him away for drug offences.
Yet Adi, nine, never once thought any lesser of his father, Ahmad, 40.
Instead, Adi continues to tell his aunt, Zila: "He's my hero."
All names have been changed to protect their identities.
It is not difficult to see why Adi fiercely stands by his father.
Zila, 38, who is Ahmad's sister, explained: "The bond between father and son is very strong.
"His father would take him to Changi Airport to watch planes take off and both of them love Formula One.
"Adi is a picky eater and used to eat only crispy food, and my brother would take him out to eat that.
"Ahmad may be a drug addict but he is not a bad person. He's a doting father and loving brother."
Adi has a younger sister, seven. The petulant girl, who is kept in the dark about Ahmad's imprisonment, screams for him to come home whenever she gets reprimanded.
"She thinks her father is doing paint jobs on a ship and will come home with a huge bag of money," said Zila with a half-smile.
Each time Ahmad is jailed, his sisters and parents look after his children.
"We try to make sure they are not left out but it's just not the same. The children feel Ahmad's absence," said Zila, a mother of two.
She takes over the responsibility of holding the family together whenever her older brother is in jail.
"To be honest, it's tiring," she said.
"I was very disappointed when my brother was arrested again. It felt like what he had said about changing for good were empty promises."
The ones most affected by Ahmad's absence are his parents, who are in their late 60s.
Every year, when Hari Raya is around the corner, Ahmad's mother would cry while cooking his favourite dish.
But the close-knit family has never given up on Ahmad. His mother visits him whenever she can.
"When someone of his age falls down, we should be there to pick him up," the 68-year-old said in Malay.
Zila chimed in: "I think my mother has visited all the prisons in Singapore because of my brother."
She added that her brother seems bent on changing for the better this time.
"I can feel the difference in him. He has already planned carefully what he wants to do and is very serious about it," said Zila.
"For instance, he was recommended to attempt the O levels but he chose to go through N levels first because he wanted to be better prepared and not take chances."
The family is looking forward to their next Hari Raya celebrations - Ahmad will be released from prison on remission.
"The children know that their father will be home and are excited to wear matching baju kurung with him," said Zila with a smile.
Prison school helps convicts
Science lab stools are chained to the ground so they cannot be thrown. Items like scissors are locked away when not in use.
Welcome to the Tanah Merah Prison School, where selected inmates get a shot at education.
The idea for the school came from former Prisons director Chua Chin Kiat and became reality when Kaki Bukit Centre (Prison School) opened in 2000.
It was relocated to Tanah Merah Prison in 2011.
The school's mission is to leverage on education to rebuild lives, enhance employability and reduce re-offending, said its principal Leong Sow Phong.
"We strive to provide a conducive learning environment to assist our students in rebuilding themselves intellectually, morally and socially for their return to society as responsible and productive citizens," he added.
The school prepares students for the N, O and A levels.
Nitec in Electronics and General Education courses are also offered.
This year, 101 students from the school sat the N-level exams.
Classes, conducted five days a week, are taught by 15 Ministry of Education-trained teachers as well as a pool of part-time teachers and volunteer tutors.
Selected students have to be of good behaviour and display attitude and aptitude for studying.
As the school believes that a successful rehabilitation for prison students takes more than just good academic results, it also offers programmes that help enhance bonding between offenders and their families, and to quip inmates with core skills like stress management.
This article was first published on December 29, 2015.
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