When baby first starts to sign, you and baby would sign just one key word while the rest of the words are spoken out loud and put into a sentence to provide your baby with context. The “key word” is the word in the sentence which carries all the meaning. At different times, depending on what you are seeing or talking about, it might include the noun, verb or adjective. For example, you might say “Look at the SQUIRREL, it ran down the tree” In this sentence, you signed SQUIRREL, while the rest of the words you just said aloud. This provides your baby with context and teaches him how language works. A young baby is not particularly interested in what the squirrel is doing (running) or anything else in the environment such as the tree.
However, once your baby has independently learned to sign TREE and DOWN, as well as SQUIRREL, you can add these to your signed sentence too. I will caution that to be most effective your baby will understand each word independently so as to avoid unnecessary confusion. In most cases, it will take quite a while before your baby will have enough words to create sentences…just because it takes so long for a baby to remember them on their own.
So an advanced signed sentence will have two or even three signed words. “Look at the SQUIRREL, it ran DOWN the TREE.” In this case, you signed SQUIRREL, DOWN and TREE.
Signing more words in a sentence is a great way to teach your baby more signs to expand their vocabulary and also keep baby signing fresh.