A three-year-old child's scribbled caption accompanying her drawing of a dog indicates that she understands writing as a:

The child's scribbled caption accompanying her drawing of a dog showcases her understanding that writing serves as a means of communicating ideas. At the age of three, children are beginning to experiment with symbols and letters as a way to express their thoughts and feelings. This early writing demonstrates their recognition that written language can convey messages, even if the actual letters or words are not fully developed.

In this instance, the child's attempt to add a caption indicates that she associates her drawings with a narrative or concept, suggesting an emerging awareness of how writing can enhance visual art by providing context or additional meaning. This interaction between drawing and writing highlights the developmental stage where children are beginning to grasp the functional purpose of written language, which is to communicate ideas, emotions, or stories to others. This understanding is foundational for literacy development as they progress in their education.