children doesn't need to know about currency,but teenagers does,and i think there's so many explanation video in youtube so don't wasting effort wasting your time when you can just give them about the link of video so they can learn from it,whether they will be interested or not,it's definitely depend on them
Its not as difficult as it seems to explain anyway just tell him how it is keep it basic just tell him all it really is like online currency that kind of runs like stock one day it can be lower and one day it can be higher. Your thinking about it hard but its rather simple I'm no wiz at bitcoin but in my understanding that is how it goes more or less.