Educators say a question which tested estimation skills in this year's Primary School Leaving Examination (PSLE) mathematics paper is fair.
They were commenting on concerns raised by some parents about the question in last Friday's exam paper.
It had asked pupils how heavy eight $1 Singapore coins were. They were given four options: 6g, 60g, 600g or 6kg.
It prompted a Ms Lee Xun Yi to ask the Ministry of Education (MOE) on its Facebook page last Friday for clarification.
"Are we having IQ exam or maths exam?" she wrote, asking if there could be more than one answer because the candidates were not told the weight of each coin.
However, some maths teachers The Straits Times spoke to said such questions are not uncommon in primary school exams, and that they test skills of estimation and reasoning.
Said a 38-year-old educator who has taught maths at a primary school for seven years: "The PSLE question is reasonable as it tests estimation and elimination, skills that we teach pupils."
And Mr Tan Weiqiang a former maths teacher who is now director of Junior Wonders Tuition Centre, said: "The question isn't about the exact weight. It is testing the pupil's ability to estimate based on the weight of everyday objects."
Estimating "mass in kilograms/ grams" is part of the primary school maths syllabus, the MOE and Singapore Examinations and Assessment Board (SEAB) said in response to queries.
Pupils learn topics such as length, mass and volume, using real-life examples they come into contact with such as their classroom door or a teacher's desk.
The PSLE papers are set by a panel of experienced school teachers, curriculum specialists from MOE and assessment specialists from SEAB. This ensures that questions "provide an appropriate and representative coverage of learning objectives" within the syllabus, said MOE and SEAB.
The pupils are "not required to calculate or have prior knowledge of the mass of the object", they added. They are supposed to "make an informed estimate based on their ability to relate its mass to the different order of magnitude given in the multiple choice".
Several parents The Straits Times spoke to also said the question was not unreasonable.
Mrs Sivakami Sundararajulu, 45, said she asked her Primary 6 son about the question after hearing about it in online discussions.
"He said it wasn't difficult and he just did it by elimination," said the housewife, whose son chose the 60g option - the right answer.
"It is just a common sense question, and they learn estimation in school quite early on," she added.