The Hardest Part of This Question Isn't the Maths.

This post is just the solution - but I want to walk through the thinking, not just the working. Because the working alone doesn't tell you why the sequence matters.

Here are the 2 versions of the questions.

What the Scaffolding is Actually Doing

The question gives you a lot of information. Two tanks. Multiple measurements. A fraction. An overflow figure. Most people read all of that and immediately reach for the numbers they recognise - and that is exactly where things go wrong.

In the first version, what's the question asking for? The height of Tank X.

Everything else are information that you need to build the path. But if you don't know what you are ultimately trying to find, you won't know what each piece of information is for.

But in the second version, you are given a smaller problem to solve first before finding the height of Tank X.

Scaffolding guides the plan. 
It doesn't replace the understanding of why the plan works.

The Plan: Sequence Over Calculation

Once the framing is clear, the plan writes itself. There are 5 things to find, in this order.

5.  Height of Tank X :  the answer (This is Part B)

This is exactly the sequence the question's scaffolding leads you through. But a student who understands the why, not just the what, can derive this plan themselves, with or without the sub-questions guiding them.

That is the deeper skill the Minister was pointing to. Scaffolding is a training wheel. The goal is for students to eventually ride without it.

The Full Working

Here is the full solution using the MathSifu Masterplan Framework. Each statement in the Statement and Solve section maps directly to one line in the Plan section. 

One Statement-> One Line.

What This Means for How We Prepare Students

As scaffolding and distributed weightage in marks is now a feature of PSLE maths, preparation needs to shift accordingly. Drilling calculation speed matters less. Developing the habit of reading a problem for its structure, before touching a single number, matters more.

A student who has been trained to ask "what do I need to find, and what do I need to find first?" will use the scaffolding well. They will see each sub-question as a confirmation of a path they have already begun to trace.

A student who has only been trained to recognise problem types and apply templates will struggle when the scaffolding runs out, or when a question's structure is slightly different from what they have seen before.

The question the Minister shared isn't hard because the maths is hard. It's hard because it requires a student to understand a sequence, and understand why that sequence is the only one that works.

That is a thinking skill. It is teachable. And it is exactly what structured problem-solving frameworks are designed to build.

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The answer to this question is (a) 7200cm^3 (b)32cm. The Minister's point was never about whether adults could get there.

It was about whether we are building students who can think their way through a sequence, not just follow one.

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Read the companion post -> “Give Back to Teacher Liao” -  This Worries Me  

→ Explore the MathSifu Playbook: mathsifu.com/masterplan