Teachable Moments

I've been thinking a lot about this lately.
What exactly is a teachable moment? And, if you're with a child - doesn't every moment qualify?
Or are they moments when I am expecting too much out of my children?
I think we had a moment like this the other day.
We (me, Caroline, Sam and Nate) were at church. The reading was from Daniel - about Shadrach, Mishad and Obendigo (or ToBedWeGo, however you prefer to pronounce it). Caroline was really excited because we had just read that story and we were talking about how God sends angels to help us everyday. The kids were really engaged and the conversation was going great (or so I thought). We were leaving church and Fr Thurb asked Sam about what he thought.
His reply?
"Lightning McQueen is the fastest race car EVER!!!!!"

Annnnnnddddd....the teachable moment is over.
It was nice while it lasted.