I talk a lot on my blog, KidzLearnLanguage, about teaching kids who use augmentative communication core vocabulary words. Core words are those words that we use most frequently, that are combined easily to form phrases and sentences, and have multiple meanings for use in multiple contexts.
We spend a great deal of time with emergent communicators teaching them beginning words with which to express themselves. But for social and academic success students need to be able to to communicate beyond single words - or even two word phrases. As with all students who lag in language skills, such skills as syntax development, narrative structure and conversational skills need to be considered.
A variety of strategies have been explored to teach conversational skills to AAC users with severe disabilities, including several that emphasize teaching these skills in natural, genuine settings. Social interactions are important in increasing quality of life, with access to interpersonal relationships, access to curriculum, and access to community resources.
Here is an example of an activity I use in intervention when more practice is needed in generating utterances beyond the single word level. SLPs use lots of pictures in therapy. Download these two pages of picture-based practice for making phrases and sentences. (I bet you thought you were done with snow.)