It is very difficult to explain the bitcoin. I also confused how it works when the first time I heard it. Since teenagers now has a lot of knowledge about technologies and social media, I think that it will be easy for them to explain bitcoin and how it gives profits nowadays.
What matters is their interest. If they are not interested in what you are saying, it will be useless. Social medias are sometimes not a good influence to teens. Sometimes it changes their perception about a thing. Just take a look at the teens that are present in this forum. They are looking at Bitcoin as a way to earn, not a money to use.
It's okay if earning Bitcoin could help them, however it sometimes make them greedy. Not good IMHO.