It seems pretty useless having a read along when the text you are supposed to read is not there/avaliable.
This is really stupid - but I shows how simple or limited these apps are the text and audio are always seperated, a good way would be if you got both in a package so you could:
Read along
Read if circumstances made listening not possible
Switch between audio and reading
You could look at illustrations in the book while especially if they are pertinent.