Trying to Use Words

As many of my readers know, some of the kids in my class have moderate special needs. I have this really bright boy who has some trouble understanding social conventions. He needs very structured and explicit teaching about certain behaviors that come naturally, or at least very quickly, to most students. We are still working on appropriate ways to ask to go to the bathroom. At the beginning on the year, he was walking up to me and grabbing his crotch. I had to stop that immediately for obvious reasons. For the beginning of the year, we developed a hand signal for him to signal to me that he needs to go to the bathroom (he holds up his index finger). This has been working out beautifully. Now, we are trying to get him to use his words. We talked about and practiced (before the snow days) ways he can tell me he needs to go to the bathroom:
"I need to go to the bathroom." "May I go to the bathroom?" etc...
Today, he came up to me and did his hand signal. I reminded him that we were going to try to use his words instead. "Oh yeah," he said, "I need to go number two."
We're making progress slowly!