Do we really need child-oriented Bitcoin content? Kids don't earn money, and don't often make payments, they most likely won't be using it until they grow up. And Bitcoin's complexity in terms of use is way to high for children - they can easily fall victims of scams or malware and lose whatever coins they parents gave them.
We must not think that our children have to acquire Bitcoin now or that they must start investing before they come of age, but we must teach them the best way to start saving and what is the safest form of savings for their future. Here in Italy a dear illustrator friend has created a small book that teaches the basics of currency up to Bitcoin and initially he did it for his daughter and then he realized that as many children as possible had to read and so now everyone can buy it with Amazon.