The first-grade student used a contextual cue to understand the meaning of the word "retreated" in the sentence. Contextual cues involve using the surrounding words and the overall context of a sentence or passage to make sense of unfamiliar words or phrases. In this case, the student recognized that the dog's action of "retreating into the house" followed the owner's call, which indicated to the student that "retreated" meant the dog went back or withdrew to the house. This demonstrates a basic form of context-based comprehension, a critical skill in reading and language development.