There are plenty of them but it will consume a bit of your time in searching one. This is really a good idea for giving the kids idea of what bitcoin is.
I did saw another thread about suggesting not to force kids into knowing bitcoin and that's also a good point.
Well it differs from the point of view of someone who like to share knowledge in bitcoin and those that are concerned for the welfare of kids so that they can enjoy their youth.
Most of the kids this days used to read comic books. That's why it's a good initiation to let your kids reading a comic book for Bitcoin. But we have to be aware not to force them because it only mean that it's not the right time. Maybe some time they are ready just wait patiently. "There is a saying that we just don't always drink milk, we also try to eat some hard food to live".
I don't think that most of them are still reading comic books. But majority of them are into those kid videos and cartoons.
But it's a good start for giving them the idea of what you're trying to convey to them as a message on what to learn. They'll soon realize that and will remember what you're doing for them.
My point here is that, don't surrender on helping your kids getting knowledge on Bitcoin, time will come that they will be ready for it, just trust the process.
Yup, the time will come but also don't overstress yourself and them in learning. Just let it come naturally.