UPDATE: Based on the comment by GarySibio I did some research and things were not as I saw them originally. This is in fact a large female and a small male Painted turtle. As the breeding season starts the smaller male swims around the larger female with the claws on his feet spread out trying to get her attention. Therefore, I have changed the name of this photo from "Turtle Parenting" to "Turtle Courtship".
Below is my initial incorrect interpretation of what I was observing:
A young Painted Turtle sticks close to it's parent. When the big turtle would dive the little one would follow. Whatever the big one did the little one would copy the motion. There were several of these parent and youngster turtle pairs in the area of the dock where I was standing. These two where the most photogenic.