What's the big deal?

I'm trying out a unit that I've never formally done before-"Big and Small, Long and Short."  I know that your kids know the difference between big things and small things, but I'm using this opportunity to gauge mathematical concepts and talk to them about several related things:

-Many small things make a big thing!  The kids worked together on a huge contact paper/tissue paper mosaic! 
-Talking to them about David and Goliath.  Most, if not all, know this story.  I want them to see that God is the hero-not David.
-Language-what other words mean Big and Small?

I'm really enjoying this unit!