We discuss words as they come up in our read-alouds. My daughter always asks me if she doesn’t know what a word means. If I think she may not, I ask her if she does and have her try to define it if she says she already knows. I have found that reading rich books with excellent language goes a long way towards giving your kids an excellent vocabulary, because they hear the words in context. I would say my two young adult daughters have really good vocabularies just from listening to and discussing words.
The closest I get to “doing vocabulary” at this point (3rd grade) is in our Cottage Press language arts book there are two readings a week that are to be listened to or read and then narrated. First they were Aesop’s Fables, now they’re selections from Fifty Famous Stories. Each one includes a list of vocabulary words to discuss or even to write on a board as Holly S describes above. What we do is before reading the story, we go through each word and I have her define them either by words or by actions (f0r instance, with a facial expression or a posture or movement, depending on the word) to see which ones she already knows. Usually she knows most of them or has at least an inkling. She likes to make a mark by each word as she hears it in the text, and sometimes she refers back to them when she’s narrating.
This is actually one of my favorite parts of our lessons, because I’m so tickled at how much language she retains. Plus, it can be humorous. : P