Yesterday when Ellie and I prayed together over lunch, she finished her prayer by saying, "The End." instead of Amen like she/we normally do.
Right now, this is approximately the prayer we pray with Ellie:
"Dear Jesus, thank you for today, thank you for the food, please help me to obey Mommy and Daddy. Amen."
I don't know what sort of prayer you're supposed to start a child out on. It's not something I've ever really researched, so I just chose something simple enough that she could understand it. I wanted her to grasp the idea that all we have is from God, both tangible (the food) and intangible (the day) and that we give Him thanks for it. I also wanted her to begin understanding the idea that when we do what is right (obey), it is by the grace of God, that He helps us follow His commands. So that is basically where the prayer came from. But, like I said, I've never researched praying with small children.
I'd be curious to hear other thoughts on praying with small children. What do you do? Do you have memorized prayers, or do you say a free form prayer that reflects what when on during the day? Do you have your children repeat after you, or do you let them say their own prayers, and starting at what age?