As Salam Alaykum,
It is important to start seeking knowledge early, even as a child, a lot of us live in places where our children are taught secular knowledge, or even knowledge of Christianity, singing about Jesus and other things at school. So, I am very happy to have found this on another forum, it is like an activity book for children, I think normally given for home teachers and normal teachers, but I am sure it can be used by normal fathers or mothers,
Islamic Activity Book 1
Islamic Activity Book 2
This is the page:
http://www.musalla.org/Downloads.html
Insha'Allah go through the books before you teach your kids, making sure all is correct.
And Allah knows best.
NOTE: There are errors, so please becareful, one for example states that Allah is everywhere, according to a sister who has read through it, so make sure you teach from that what you know to be correct.