I like the cute example with an acorn on the field. A kid and mother comes close and the kid asks "Why is there an acorn there?"
In backward-thinking mode the mother now can respond by telling how it got there. Look back and explain. As in:
"Well, maybe a squirrel dropped it there" or "The large tree over there dropped it" or "Maybe a kid or animal played with it and just left it there."
All good responses. And only imagination limits the kind of answers the mother can give.
In forward-thinking mode the response looks into the future. As in:
"It is there to grow and become a large oak tree" or "It is there to become a squirrel dinner" or "It is there to be found by a kid. And the kid will play with it."
Switch between these forward and backward modes when answering questions. Not all why-questions has to be answered based on the past.
And many times it is more interesting what will be or become - than what has been.
There is sometimes also a non-thinking-mode when answering questions. How about if the mother in the above example answered:
"Shut up and keep walking" or "How should I know? I didn't put it there!" or even "Don't you learn anything in school?"
So, Think when you respond. And use both forward and backward thinking. And practice forward-thinking to explore and shape the future!