Although in a sense this entry is about communication.
Yesterday Kevin learned how to clap his hands and yell "yea" at the same time. We all did it with him a hundred times. And then he discovered if he did it first, we would do it back. Communication. It was like the scene in The Miracleworker when Annie gets Helen to understand the sign for water.
Think of the complex action Kevin has learned. He can bring his hands together, he can yell the same sound each time. He do it in response or do it to evoke a response. He can reproduce the same action.
I had my children at age 22 & 23 and this sort of revelation escaped me. I was just looking for the big moves. We only had Dr. Spock to guide us. Glad I'm old enough now to appreciate the small ones now. Yeah, Kevin.