We checked out the ant spot again yesterday, and it's looking really good. It's amazing how many little pieces of grass, rock, twigs, etc., they put together to build their home.
Here is a picture of their home taken yesterday:
Here is a close-up of their home. See the little pieces of grass, twigs, and gravel (and ants -- the ants have red heads)?
Here is a close-up of a couple ants:
Here is a free printable for children which shows the parts of an ant:
Here is a short video of them crawling around: