Kids will not understand the nature of bitcoin but surely they can get a small concept of bitcoin and that is saving! If you save, then you will earned a bulk of coins.
They will not understand it in their first hearing it but if they will start to do some research about it since internet has a lot of information about it. And if they will take time to read articles regarding it, they can even know what bitcoin is without having someone to guide them but only their computer. Kids on this generation are very brave and smart, they are risk takers and also wants to try everything beyond their curiosity.