In a dormitory room in Tuas that he shares with 14 other men, Mr Ashraf Rahaman, 25, sits on his bunk bed, listening keenly to his lecturer explain theories of statistics and dynamics.

The scaffolding supervisor is attending his first online class for a diploma in mechanical engineering from Singapore Polytechnic.

His Internet connection is unstable and the streaming gets cut off occasionally but the hiccups do not dampen his enthusiasm.

He overcomes these technical problems by rewatching the lectures, which are recorded, and asking his classmates for help.

"This is my dream come true, to study while working in Singapore," said Mr Ashraf, who is learning again after finishing high school in Dhaka, Bangladesh, seven years ago. "Back home, there are not many opportunities to do both at the same time."

But these aspirations come with a hefty price tag.

He will have to fork out a third of his $1,600 salary each month, adding up to more than $16,000 over the next 21/2 years.

To support his educational pursuits, his company is still paying him a full salary even though he will end work an hour earlier to attend classes three days a week.

He joins a growing list of migrant workers who have invested their salaries in courses, diplomas and degrees from various institutes in Singapore. They say their studies have paid off, and some earn up to four times more.

Over the past year, private educational institute PSB Academy has seen an increase in work permit holders enrolled in its courses, from technical qualifications to diplomas to degrees.

A spokesman said the trend is expected to continue this year.

PSB Academy graduate Faiz Ullah, 27, saw his monthly salary jump from $600 to $1,400 after he completed a diploma in electrical engineering in 2017.

The shipyard electrician from Chattogram, Bangladesh, came to Singapore in 2010. After obtaining his diploma, he was promoted from site supervisor to assistant engineer. In his new job, he manages 15 workers who check and maintain equipment.

"I wanted my parents to feel proud that their son is educated. We have good opportunities to study in Singapore, so why not?" he said.

TIME, SWEAT AND MONEY

To earn their diplomas, workers such as Mr Faiz used to commit to a hectic routine three times a week: leaving their work sites early and taking public transport to their three-hour evening classes.

They would return to their dormitories only around midnight as classes usually ended at 10pm.

"The first time I went back to the dorm after class, I could not collect my uniform from the laundry as everyone was asleep," said Mr Faiz. "Sometimes, by the time I reach the dormitory, there is no more rice to eat."

During the dormitory lockdown, taking their classes online gave workers more time to focus on learning, even though some said they still prefer physical classes which give them more opportunities to clarify their doubts.

Mr Ashraf, who began his education under these circumstances, successfully got through his first semester at Singapore Polytechnic.

Persevering with studies also benefited Mr Ibrahim Khalil, 41, who spent three years to earn a diploma in construction engineering from BCA Academy in 2018. It is the education and training arm of the Building and Construction Authority (BCA).

Once a construction worker who mainly handled plaster and concrete, Mr Ibrahim, from Cumilla, Bangladesh, is now a technical officer at infrastructure consulting firm Surbana Jurong.

His new higher pay enabled him to upgrade his visa from a work permit to an S Pass last year. After a decade of staying in dorms, he moved into a three-room flat in Jurong West that year, sharing it with four other workers, and could work from home during the circuit breaker period.

"Now my next target is to save money to set up my own small business back home," he said, adding that it would focus on consumer products.

Mr Jaggupalli Venkateswararao, 33, from India, has a different target - he wants his wife and two sons to join him here.

"Singapore is the best place to study so, at least for some years, I want to serve and give back to the country by staying on in the same job and contributing my skills to the company," he said.

The mechanical integrity inspector at Dow Chemical has spent almost $70,000 on education and training since coming to Singapore as a welder in 2006. This includes a degree in mechanical engineering from the National University of Singapore and technical inspection certifications from the American Petroleum Institute.

SUPPORTIVE EMPLOYERS

Mr Venkateswararao said learning would have been impossible without a supportive supervisor who allowed him to leave work early to attend evening classes.

His former supervisor, Mr Quek Hung Ling, 58, encourages workers to pursue further education as he believes those with ambition and a positive attitude deserve a chance at better jobs.

"I believe in lifelong learning for everyone because I was not highly educated and I have benefited from adult education," he said.

He also believes better-educated workers perform better at work, which in turn benefits employers.

Mr Quek embodies his own philosophy. He started off as a construction worker 30 years ago, and is now a managing director of his own firm, ProEn Scaffold.