I used a very simple illustration for the idea of returning thanks to God for what we have been given.
Asked "who's had a birthday party?" Hands go up. "Who's been given presents?" Hands go up. "Do you ever get to write thanks you notes? I did when I was a kid...still, do...sometimes."
After each kid who wanted to share does, we talk about how God puts gifts into our lives everyday. Then I asked, "How can you give thanks back to God for the gifts in your life?" Prayer, worship, sharing the gifts...others.
Then we offered thanks back to God in our closing prayer.