9 yo has his own g-mail account. I sometimes send him messages there.
A few days ago I sent him an e-mail asking whether he would like to go through Rosh haShana shemone esre, now that he says weekday one all the time. Last year I showed him the basic structure, but he was not davening the full shemone esre yet, so he could not appreciate fully the changes and additions.
Yesterday I got his response: "No thanks."
Oh well, there is always another year. There is always a very long Rosh HaShana davening and maybe he will look inside the siddur then. Good thing I did not spend hours preparing and fantasizing about how lovely it will be, mother and son, sitting down and learning all about Rosh HaShana.