There are several songs about "Thanks" in the Children's Songbook, so we have been quickly learning a few.
One easy one to do (and one that most probably know already) is
"I am Glad for Many Things" -Children's Songbook pg.151
For this one, I started telling them what I was grateful for: my family.
Then I cued the pianist and sang the song for them.
When we finished, I had my "boing" ball and asked them
"What are you grateful for?"
I then tossed the ball to a child with a raised hand. (When they catch the ball, the ball goes "boing!"...at least most of the time...sometimes they had to punch the ball again....) They said something they were glad for and tossed it back. I did this for 3 or 4 children, then we sang the song again.
**I got my "boing" ball at Fred Meyer's for about $10.00