Telling children about bitcoin will not be a problem, because there is nothing wrong with educating children with positive things, one of which is by telling them what bitcoin is.
but when it comes to investing, it's not time for children to think about things like that, children are only required to study.

I write like this, because I experienced childhood of course , and I think that when I was a child I tended to play more, go to school, and not think about how to make money, let alone invest.