@chrisking,
chrisking wrote:the young students in my class always want a clear answer to such grammatical problems even thought there might not be one at all.
There is a thing that teachers know about called the "pedagogical lie". The concept was also named the "lie-to-children" by Terry Pratchett, although it considerably(!) predates him (see e.g. the Buddhist Upaya ("expedient means") & "Plato's Noble Lie".)
A lie-to-children, sometimes referred to as a Wittgenstein's ladder, is a simplification of technical or difficult-to-understand material for consumption by "children", (i.e. anyone in the process of learning about a given topic, regardless of age). It is itself a simplification of certain concepts in the philosophy of science.
To present a full level of complexity to a student or child all at once can be overwhelming. Hence elementary explanations tend to be simple, concise, or simply "wrong" — but in a way that attempts to make the lesson more understandable. Sometimes the lesson can be qualified, for example by claiming "this isn't technically true, but it's easier to understand". In retrospect the first explanation may be easy to understand for its inaccuracies, but it will be replaced with a more sophisticated explanation which is closer to "the truth". This "tender introduction" concept is an important aspect of education.
Such statements are not usually intended as deceptions, and may, in fact, be true to a first approximation or within certain contexts. For example Newtonian mechanics, by modern standards, is factually incorrect, as it fails to take into account relativity or quantum mechanics, but it is still a valuable and valid approximation to those theories in many situations.
The term "Wittgenstein's ladder" stems from proposition number 6.54 in that author's Tractatus Logico-Philosophicus which reads:
My propositions serve as elucidations in the following way: anyone who understands me eventually recognizes them as nonsensical, when he has used them - as steps - to climb beyond them. He must, so to speak, throw away the ladder after he has climbed up it.
There is a fuzzy boundary between widespread misconceptions versus lies-to-children. One significant difference is that genuine misconceptions are resistant to further instruction, and are often believed firmly (sometimes passionately) by adults. On the other hand, students will easily recognize and discard the lies-to-children as more advanced concepts are acquired. Another significant difference is that a lie-to-children will tend to be an approximation of the truth (e.g., acceleration due to gravity=10 m/s²) while a misconception will often simply be wrong (e.g. tongue taste map, coriolis-in-the-bathtub).
