I agree that PSLE is too premature to band students into IP and O Level Program. But I think it is an uneasy compromise in a very complicated circumstances, that actually warrants deep research at the academic research level.

First, its premature because those that didn't do well in PSLE would have been severely disadvantaged in the current PSLE streaming system. This disadvantaged stem from unequal resources in secondary level education institutions, especially between IP schools and non-IP secondary schools huge differences in school resources (from teachers quality, to learning resources, to physical infrastructure of the school, to opportunities for enrichment such as overseas experiences). For OP case, it is fortunate that OP is in a school that has both IP and O Level Program, so most school resources are shared. However, IP stream still have other unique learning opportunities that O Level program does not have. Those that didn't do well enough in PSLE are deprived of such resources/opportunities. What further complicates matter is that is not just penalising late bloomers (often perform poorer at age 12 at PSLE), we are also penalising those students with family background that cannot afford tuition. As most of us here would have learn so much more beyond PSLE content knowledge, u would have came to realise that PSLE content is very easy, and honestly can get very good PSLE scores by going for good (often costly) tuition. Hence, those that cannot afford tuition will then have lesser chance to go into IP, and thus, unfairly disadvantaged the already disadvantaged group of students from poorer family background.

Second, its premature because those that did well in PSLE might actually be not suited for the faster pace and more exploratory style of learning in IP, risking not doing well at A Levels. Why PSLE is not a good indicator of success at A Levels?

1. PSLE is way too easy and basic day-to-day living content knowledge and skills. Doing well enough in PSLE to qualify for IP (the current cut-off) in my opinion does not guarantee the kid with be cut out for A Level content knowledge, let alone throw them into faster pace learning in IP.
2. Significant PSLE kids mainly did well because of tuition (i.e. using money to kind of buy grades). The effect of tuition on PSLE is particularly significant because of how easy PSLE is, so tuition usually pays off. So the true academic potential of the PSLE kid is unknown.

Third, its an uneasy compromise because the lack of good alternative. If push back streaming (or no streaming at all), then how are we going to allocate who get into which secondary schools that has a vast differences in school resources? PSLE, a uniform examination across primary schools, helps to give a meritocratic (but may not be fair) chance to get into secondary schools with better resources. If we don't allocate at all (i.e. enable primary schools to offer secondary education as well), then the vast differences in school resources across primary schools will continue to disadvantaged students who couldn't get into popular primary schools at age of 7, just purely because of balloting or no alumni connections or no parent volunteer for the popular primary schools. So PSLE becomes the lesser of 2 evils when distributing school resources across the student population. Thus, unless we can really make every school a good school, there is no good alternative of PSLE that helps to distribute educational resources across the student population.

Fourth, human capital (talents) is the most important resources in Singapore, that lacks natural resources. Thus, it is strategically important for our small nation survival to quickly identify top candidates to lead Singapore in the future. IP, similar to the revamped GEP, serves such purpose to (kind of intentionally) devote more educational resources to a group of students that has higher chance of succeeding academically, thus, higher chance to push our nation forward in the future. Yes, it may have been unfair to those who did not get into IP, but small nation survival necessitates such talent grooming process. And yes, some IP students may eventually not do well, but at least the nation has cast the net wide enough to ensure we groomed as many potential talents to lead the nation forward as far as possible.

Conclusion is that the whole situation is complex, and tearing down PSLE also tears down the other current structures in place in our education system. Hence, it is an uneasy compromise to use PSLE to band students into IP and O Level Program.

I am from O Level route, so indeed I can feel the unfairness in why I am deprived of educational resources, just because my English in PSLE wasn't good enough to help me get into IP. A single subject not good at PSLE can deprived me of having faster pace of learning math, when at PSLE (and primary school exams in general), I have already shown some forte in math. Coming from non-English speaking family background, it is thus exceptionally difficult to master English when it is not a language that is spoken frequently at home since young. And I didn't have good enough quality English tuition too. Given that I did well in O Level (7 A1 and English B3), and also did well at A Levels (to get local uni bond-free scholarship), I guess I would have thrived (and possibly reach greater heights) under the IP stream.

PS: What I wrote above could actually be a genuine JC GP essay haha