Bitcoin is difficult to explain. I also felt difficulties in understanding bitcoin for the firs time. Let's share how to explain bitcoin to children of teenagers. In My country I can say 98% children don't know bitcoin. In fact, bitcoin can be future money. If the children not familiar with cryptocurrency or bitcoin, how can they face the digital era in the future.
Explaining is difficult specially when they don't want to listen or if they are not interested. So my tactic of explaining to them is letting them to experience first the beauty of bitcoin. And then as time goes by, curiosity will take over them. they are children after all.