During my early childhood education I was introduced to the idea of a running record. I have really liked this way of recording a child's actions, and have used it periodically since my oldest was born. All you do is follow the child around for five to ten minutes or so and write down everything they do.
Here is one I just did of Seth at 2.5 yrs:
Seth was getting into something, his sister said, “No, no Sethie.” He looks up at her innocently and says, “I Fred.” Then he came in and told me, “I Mom.” I said, “No, I’m Mom.” His response was, “You Seth, I Mom.” So I began to pout and said, “Mommm!” He says, “Yes, sweetie,” in the cutest high-pitched voice. I told him I wanted my nana, “I get it, sweetie. You tired?” He ran off to get his blanket, but soon got distracted by a book. All of the characters in this book have noses. This is very exciting. He points to several noses and says, “a nosey, a nosey, a nosey.” He shouts, “Nose!” in delight. He sees Thomas the Train in a picture and says, “Thomas! Thomas where are you?” He begins commenting on other pictures, “He’s going swimming. Ooo, what shall he do? He hab a train, Thomas. Thomas! Thomas? James, where are you? Come here Thomas. Shoo, shoo, choo.” He looks up at me, “You want a milk? You want to go to sleep?”
The nice thing about these records is they can show how many words the children are using, what their interests are, and how often they move around. It is like a little snapshot in words.