This is a mud turtle, very common in our area. This is a rather large one, usually they are about four inches across and five inches long.
It's beautiful under shell. It has a lot of scratches on it so it must have crossed a road or two.
The kids put it in the duck pool to observe it swimming. They put a couple leaches in the pool hoping to see it catch and eat them, it but it didn't. They decided because it was so far removed from it's habitat that it was too nervous to eat.