Ofcourse it is very hard to explain bitcoin to children or teenager. But if i face this problem. So explain their very simply. I will tell them bitcoin is a currency like usd and other currency. But bitcoin is a online currency. That simple.
Teenagers now a days especially those Millennials are easy to teach. They have their mobile phones always with them as bthe are at pace withh technology. I just introduce to them that is the same as our money where they can also use too purchase online.