Ming from Agents of Speech explains how caregivers can intentionally misunderstand or withhold help to push children with limited vocabulary into longer sentences. When a child says "peanut butter," pretend to put it in the fridge instead of opening it, so they have to clarify with a complete phrase.
When we're talking about children who are stuck at I want are usually children who do not have enough vocab that are functional, don't have enough verbs, and therefore they will be stuck trying to imitate you. Get rid of the I want, because it's not effective. What you want to do is to start to sabotage the communication. So sabotage the communication means if the child says peanut butter, they haven't told you exactly what they want you to do with the peanut butter, so you act like you don't understand, and then you do something else. So for instance, they say, peanut butter. Oh, peanut butter. And then you put it in the fridge. Obviously they're gonna say no, right? So what do you mean? And then that's the way to teach them something of a longer sentence that has meaning for both words. Then they have the peanut butter, and then they can't open it. They give it back to you. You can ask, what do you want? But you have to give the solution as well. Oh, open peanut butter. What do you say? Open peanut butter. And then after that, you just give it to them. You need to sabotage the communication and don't let the context do its work.
