When some 200,000 pupils descended on the MC Online e-learning portal over the last two days to do their homework, the website crashed in what was the most severe outage seen in years.

School was out for these Primary 1 to 5 pupils on Thursday and yesterday due to the PSLE oral tests.

They were instead given online English, mathematics and science assignments - most of which are hosted on MC Online by Marshall Cavendish Education, the largest e-learning services provider for Ministry of Education (MOE) schools.

The outage lasted throughout Thursday before service was restored, although with slower loading times, according to many parents. Yesterday, MC Online posted a notice saying it had done "urgent maintenance" and urged users to refresh their computer screens to regain access.

Housewife Sakura Siow, 43, said MC Online displayed the message: "Urgent maintenance of the website is taking place and the website is not available for public access."

She said of her daughter's assignment: "It took us 10 hours to finish a one-hour task."

Housewife Pauline Tan, 42, said there have been issues in the past, adding: "The website is often very slow during peak hours to the point that it kicks you out."

Her three children, aged seven, nine and 11, could not access MC Online on Thursday morning.

Art educator Heng Li Ching, 45, discovered the problem on Wednesday evening when her eight-year- old daughter tried to finish her homework early. "I'm so used to this," said Ms Heng, whose 12-year-old son went through the same ordeal over the last few years.

A Marshall Cavendish Education spokesman said an existing arrangement with third-party vendors to automatically increase capacity "was not activated", which led to the outage. "We have alerted our service providers and have been working with them to resolve the issue," she said. She added that there has been an "unprecedented" sustained spike in the use of MC Online in recent months. This, coupled with recent security enhancements against malware, could have contributed to intermittent access.

Workshop trainer Liu Yunni, 47, worries that Singapore is not ready for a nationwide school closure in the event of a pandemic or haze. "Schools promote e-learning to prepare for such emergencies, " she said. She hopes that the upcoming e-learning portal, dubbed Singapore Student Learning Space (SLS), will have sufficient capacity during such emergencies.

SLS is set to become a major part of the education system from next year and will host the materials of major subjects. It is being developed by MOE together with GovTech, the agency behind tech transformation in the public sector.

An MOE spokesman said: "As the SLS leverages cloud technologies, it (will be) able to meet surges in capacity." She added that SLS will also be compatible with most devices, including the Apple iPad, which does not support Adobe Flash videos.

"Schools have the autonomy to use the resources on the SLS or continue to use commercially run e-learning sites based on the needs of their students," she added.