Child: aaah, aaaah… wannna raaaai…sin…!! raaaiiisin!
You: Joey wanna a raisin?
Child: yah, yaaah!! raaaisin!
You: OK, here’s a raisin for you.
Moms usually have such good sixth sense of what their children want, no matter how butchered and mangled the requests have been stated by their children. Rephrase the primordial grunting and pseudo-English into human language then you’re good to go.
If they start with anything but a civilized verbal request, make them ask. Teach your children to ask for things by using “words,” even if those words are not coherent. Mastery of pronunciation, sentence-forming, and grammar will all come later.
Otherwise, once they’ve mastered the asking process, it’s time to make them wait.