I have a very easy way to tell Bitcoin to children and teens. I can explain bitcoin which is digital money in a simple way if i explain the difference of money in debit card or cash. They are very intelligent entities and understand everything about the computing environment very well. It is very difficult to tell about Bitcoin to the old than children and teens.
That would be easy but not all kids are really interested with bitcoin, even those people who are old enough most of them are still not interested with bitcoin, I think we should evaluate their interest and capacity first before we will start educating them, it's necessary to ensure our effort will be appreciated and we will be able to help them fully understand bitcoin because they will venture on it.