When you talk about children and praying .. I still remember how different myself and my granddad's approach with children ..
As for me, my daugther just one day approach me and ask me why I pray everyday. And told them that praying is to something we need to do as a muslim. Praying builds up good character and such. Then , I ask her, do you want to pray with me and mom? Just like that, she started praying. And because she started to pray, my son join in as well.
It is the same thing when she start reading books. Me and my wife will read before going to sleep, and then one day she came and sits beside me and read her comic book.
Now my granddad is a bit different, He will say this:
Haizrul : Grandad ... i dont want to pray magrib today .... I am tired
Grandad : Haizrul ... Do you want to go to Hell?
Haizrul : errrr no
Grandad : Then get wudhu' and lets go to the mosque now .....
Haizrul : ok