Embedded questions

My plan is to tackle one English mistake at a time, and try to explain why the grammar is incorrect. Today I heard someone say: "Do you know where's Robert?" Within the overall sentence (question) we have the question: "Where's Robert?" In this kind of sentence, the embedded question cannot be put into the sentence as it is. Let's recreate the sentence. Do you know X? X= Where's Robert? 1) Make the question X into a statement (by making up an answer): Robert is at the store. 2) Replace the unknown part (in bold) with a WH-word (who, where, when, etc): Robert is where. 3) Move the WH-word to the front of the clause: where Robert is 4) Embed the clause in the sentence: Do you know where Robert is 5) Add the question mark: Do you know where Robert is? (correct sentence) So, in the correct sentence "Do you know where Robert is?" the 's of where's was changed to is. (We can't have: "Do you know where Robert's?" We just don't use that contraction in English). I hope this makes sense.