Written and spoken communication are different things, but you can’t pretend they aren’t extremely closely linked. My point still stands—an ability to understand subtext is a factor of reading comprehension.
I am familiar with the concept of subtext, thanks. I think you’ve mistaken that what is incumbent upon you here is to demonstrate what subtext has been contained within the text as you put it, in either the OP or my example, that was missed.
I mean in the case of my old school memory I think you’ll just have to indulge my recollection that there was none (in fact, that all subtext in that situation related to being in math class etc purposefully indicated that it was a genuine math question, by the teacher’s design). But in the OP greentext parable, literally some text presented devoid of context, which actually is relevant in that it establishes that there is a closed loop of literary conventions in that text which can be analysed or ‘comprehended’ - what is the subtext?
In the greentext, the question is posed: which is better, small boobs or large boobs? Rather than explicitly telling the man “neither is better,” the Great Philosopher uses a metaphor to help the man come to that understanding himself. The subtext is that it’s an invalid question; despite their differences, neither is better, just as $30 in coins has the same monetary value as $30 in bills.
The ability to recognize when a question is itself invalid is important to reading comprehension, and you cannot fully understand a concept if you aren’t capable of declining to take statements about it at face value. You may have read that it isn’t possible to influence the roll of a die before that test, or you may have assumed that it isn’t, but if simply seeing the question “how can you influence the roll of a fair die” makes you think that it must be possible, then you didn’t understand that it isn’t. Had you had better reading comprehension at that time, you may have been able to answer the question correctly without any further context needed. All you needed to do was not assume that the question had an answer.
Of course, that’s not very appropriate for a math class. Better to teach students that in… Social studies? It’s been such a long time since I’ve been in school, I can’t even remember what class is meant to teach literacy.
Your interpretation of the subtext in the OP is predicated on context which does not appear in the text. Answering a question with a metaphor implies that the metaphor will demonstrate an answer to the question; nothing more. It does absolutely nothing AT ALL to suggest it is an invalid question; you’ve just made that up. The respondent being analysed has in fact recognised this subtext equally and their resulting lack of understanding has happened in spite of this.
In my math class example although the test question was a written question, I received it in person in math class in middle school in rural Australia during late 90s from a teacher and as a part of a syllabus I was familiar with. These are just some examples of the contextual clues which in combination with the text formed the subtext or the basis for my interpretation of it. There are other circumstances I’ve not mentioned because they are irrelevant to the point I was using the example to make, and it’s none of anyone’s business. That said, it is just plain ridiculous to argue about the subtext of a question paraphrased in recollection after decades as if my original comment has somehow given you a more accurate read on the experience I lived.