This year's Primary School Leaving Examination (PSLE) mathematics paper left some pupils in tears and drew a backlash from a few parents.
Some questions from the second section, known as Paper 2, were exceptionally difficult, parents told The Straits Times.
Three questions were shared online after the paper last Friday and a Facebook post by a parent airing her grievances on Monday was shared more than 1,000 times.
This is not the first time tough maths questions at the PSLE have been in the spotlight - parents also took issue with "tricky" questions in 2015 and 2017.
Legal counsel Chia Su Anne, in her 40s, said her friend saw pupils leaving school after the paper with "puffy red eyes", while her son said it was harder than his preliminary papers, but manageable.
"We just moved on to the next subject paper, without analysing how he did, as we didn't want him to feel demoralised," Ms Chia said.
Counsellor Cheryl Sim, 49, said her son had also found the exam tough. "He felt so down after the paper. So we gave him more support for the last few papers."
Others felt the questions were manageable.
Parent Michael Ma, 44, said he had talked to his son and looked at the questions circulating online. He felt they were "tricky", but not out of the syllabus scope.
"These questions could differentiate the best pupils from the good ones," he said. "With a good understanding of the syllabus, a pupil should be able to do well."
A spokesman for the Singapore Examinations and Assessment Board said questions in all national exams are based on topics within the syllabus. The aim is to "assess students' ability to understand and apply concepts". He added that there is a balance of "basic, average and challenging" questions so that standards are maintained from year to year.
The Paper 2 exam was 11/2 hours long, comprising five short-answer questions and 12 long-answer ones.
Educators said it is typical for some questions every year to be more complex and require some level of creativity.
One question asked pupils to figure out patterns in a set of triangles, while another required them to find the diameter of a circle, given a set of semi-circles and measurements.
Mr Wallace Wong, co-founder of tuition centre Study Room, said the questions did not involve technical maths skills such as a deep proficiency in algebra.
"It just takes patience and the ability to stay calm in the exam hall to try different methods of visualising and solving a question."
But parents said it was unreasonable to expect children to think creatively under pressure and time constraints.
Ms Goh Su-Ling, 47, who works in a charity organisation, said some questions seemed more a test of IQ than maths skills. "The standards seem to be higher than what is to be expected of mainstream children."
Senior clinical psychologist Jessie Chua said encountering a difficult exam can cause anxiety and stress - a normal reaction. But these pupils may be too young to process the situation, "with some possibly believing that they have failed terribly".
She urged parents to remind their children that "a difficult exam is not representative of one's self-worth, character or intelligence".