On a whim, I asked the kids this morning, Why do we do communion?
W, "'Cause it's how God loves us."
K, "it shows us the new covenant in Jesus' blood."
Then after I picked my jaw up off the floor K asked, "What does covenant mean?"
I told her it was God's promise and said maybe I'd say it that way next time so people would understand. She said, "No that's not how you always say it, and you should say it the way you always do. Now I know what you mean, though."
This is why I don't care one bit if kids "understand" communion by any of our standards before they start receiving it. They get it so much more than we can ever really teach them anyway.