Children no need know about bitcoin right now . After they growing up then they will received information anywhere and anytime . If i want explain to my children , i will say bitcoin is online cash with online wallet . i can using it to buy something from who will accept bitcoin .
Children is a no go with bitcoin. They will be dead bored if you will be talking about bitcoin and investing, but it is the opposite on the teenagers since they are close to what we call the reality principle.
Also, with how you will be explaining bitcoin to your children, better point them out some sites that will be helping them rather than giving explanations complicated like what you have said.