This week I noticed that my son was constantly pointing out nouns to me - and yes, he was pointing out pretty much everything! He gets the distinction between common and proper nouns as well. When I needed a chunk of quiet time to read aloud with my daughter, I had my son do an activity to solidify this concept.
I'm sure you have lots of these around your house (I save them for these occasions):
I told my son to cut out pictures of nouns.... and he came up with a lot of things to cut out! All on his own he went to the costume catalog and starting cutting out pictures of super heroes. "Here are a bunch of proper nouns, mom!" I was so happy to hear him make the distinction on his own.
I gave him a couple pieces of paper, a glue stick and wrote "Common Nouns" on one piece of paper and "Proper Nouns" on the other piece. He arranged them all very carefully before he glued (he's my type A child):
Without any effort, he has also memorized the poem "The Caterpillar" by Christina Rosetti (also in the book). We didn't even work on it; we just repeated each day during our lesson and all of a sudden he knew it. I haven't yet read The Well Trained Mind by Susan Wise Bauer, but I have it reserved at our local library and can't wait until it gets here!
It struck me today not only how much I have yet to learn about this thing called homeschooling, but also just how blessed I am to have the opportunity to learn!