More pupils sitting the revamped Primary School Leaving Examination (PSLE) may have to undergo balloting to sort them into secondary schools under the new scoring and posting system.
With wider scoring bands replacing the current T-score system in 2021, more pupils taking the national exam are likely to come away with the same scores.
This could lead to more computerised balloting if many select the same secondary school.
Education experts noted that balloting may be more prevalent. Dr Timothy Chan, director of SIM Global Education's academic division, added that even with balloting coming in as a last resort to sort pupils into schools, "a couple of extremely popular schools may still be oversubscribed".
However, the Ministry of Education (MOE) anticipates that balloting will affect only a small group of pupils as it would take place only after two earlier tie-breakers have been used. Under the new system, computerised balloting will be the third tie-breaker, after citizenship status and school choice order.
Based on past cohorts' performance and choice patterns, about one in 10 pupils would have to undergo balloting, according to MOE.
Posting will continue to be based on academic merit first.
When pupils are tied for a place in a school, citizenship status remains the first tie-breaker.
The choice of the six secondary schools, however, will now count for more, as choice order will be introduced as the second tie-breaker.
Currently, when two or more pupils are tied for a place in a school, a computerised ballot will be used to determine the posting, even if one pupil had indicated the school as his first choice and the other had placed it lower in his list.
But under the new system, if there is a tie, the one who places a school higher in his choice list will have priority.
Housewife Karen Wong, 37, who has a five-year-old son, said choice will matter more as many pupils would end up with similar PSLE scores. "The wrong choices might even close the doors to a relatively good school my child could have got into," she added.
Ms Cha Pei Pei, vice-principal of an enrichment school, added that parents may need to manage their expectations. "The reality is that not everyone can enter an elite school," said the 37-year-old, who has a five-year-old daughter.
Using choice order as a tie-breaker may encourage parents to place greater consideration on factors such as a school's culture, its distance from home and the unique programmes and co-curricular activities that it offers.
Secondary schools here now include distinctive programmes to nurture interests beyond books. By next year, all secondary schools will have an Applied Learning Programme and a Learning for Life Programme.
The first helps students see the relevance of what they learn, for instance, in science and technology or business and entrepreneurship. The other helps develop character and skills such as teamwork through school expeditions, sports or the arts.
Education experts such as National University of Singapore lecturer Kelvin Seah said the new posting system will likely push pupils, and their parents, to consider the schools' niche programmes and whether these match their interests or talents.
"It encourages parents to think hard about how they rank their child's preferences and to make deliberated choices," he added.
"The costs of making a hasty and thoughtless decision is now much greater."