Having worked as a nanny with toddlers (11-23 months) for two families, convincing toddlers to use the words that they are capable of using can be a battle. You have to stand strong and keep encouraging them to use their words, for instance, there was the one family that I was with and they had toddler twin boys and they didn't communicate when they were hungry. I got to the point that I had a pretty good eatting schedule, but then I added words to it and the word that the boys picked up on was "snack" and when they wanted to eat they would come to me and say "nack, nack, wease," which translated to "snack, snack, please." The boys then picked up on "no nap" at naptime and "nigh, nigh" when they were tired. I encouraged every word, including "all done" and they learned with me that "all done" meant all done. Their sisters where "issie" short for "sissie". The last little girl I was with learned a lot of words...from tv (which her family wanted on 24/7 on nick jr, scary that I can still sing the songs a year later), from her grandparents, her mom, and I. We all repeated words (often without realizing that we were repeating the same thing until we talked about her new behaviors) and the more words that we repeated, the more that she picked up on and repeated back to us. She had an amazing vocabulary for just barely two when I left her and her family, well over a thousand words. My best advice to help babies learn words is just keep talking to them, reading, singing, playing with them and encouraging speech (the words don't have to be perfect, they'll get clearer as they learn more words).