Push them to be better spellers, speakers, and ultimately writers! As vocabulary increases, so does fluency in speech and writing.
Here is a packet of various activities I use with my spelling words and our unit vocabulary. I've been so surprised at "spelling lists" and books that include words that the kids don't know.
These activities can be used with spelling lists, literacy or spelling centers, novel studies, unit vocabulary... anything! One of the posters is simplified a little for lower grades. Enjoy!