Oh boy. Your response and the word teenagers inspired me to think of another creative writing exercise. This one might be a little challenging? But it can be altered quite a bit.

So we have pangrams - sentences which contain every letter of the alphabet. "The quick brown fox jumps over the lazy dog" is probably the most well known. Here we have a pangram, which is just a fun thing to know exists when studying language, and we either rewrite or respond to it in a way that acknowledges the sentence, but emphasizes the elements of language that lead to sonic prosody: onomatopoeia, alliteration and rhythmic effects. I also like to use figurative language, which is rather related but different, and I'll get into in a second.

I personally lean a lot on alliteration and rhythmic effect in these examples, but you can obviously play around a lot to adjust or alter this sort of exercise. The point is to give a known form and ask the student to respond with what they know. That same teacher I mentioned was also my freshman English teacher and she gave us an assignment to rewrite the famous balcony scene in Romeo and Juliet using new language from a different mode of speech or character archetypes. She gave the example "surfer and valley girl." I remember I did the exercise using chatspeak! Which she didn't get at first and gave me a C for the exercise, and then crossed it out and gave me an A (lol).

Anyway, here are a few examples of this exercise, "Responding to pangrams with prosody":

To respond to your question, "At what age do children lose their innate curiosity to the system?" I personally recall getting so stressed out about how my grades would affect my future starting in middle school, when it was revealed our grades in middle school would affect our high school placement, and that the high school placement and those subsequent grades were the major determining factors in what colleges we could go to.

However, in middle school too I had a passionate English teacher who introduced us to figurative language and gave us a lot of figurative language exercises and personally encouraged me to get interested in rhyme (I remember getting myself a rhyming dictionary for Christmas lol). Figurative language and even rhyming exercises may also be appropriate conduits to teaching creative thinking in a language setting.