Which factor primarily influences a student's reading comprehension as demonstrated in a comprehension assessment?

The primary factor that influences a student's reading comprehension, particularly as measured in a comprehension assessment, is vocabulary knowledge. Students with a rich vocabulary are better equipped to understand texts because they can grasp the meanings of words and phrases as they encounter them. This understanding allows them to make connections, infer meanings, and fully appreciate the nuances of the material they are reading.

While decoding skills and reading speed are important components of the reading process, they serve more as foundational skills rather than direct indicators of comprehension. Decoding allows a reader to translate written text into spoken words, but without adequate vocabulary, the meaning may still be lost. Reading speed can also vary and does not necessarily correlate with understanding or processing the information effectively. Interest in the topic can enhance engagement and motivation, which may support comprehension, but it is vocabulary knowledge that fundamentally enables a reader to extract meaning from the text they are reading.

In summary, vocabulary knowledge is essential for comprehension because it directly influences students' ability to understand and interpret what they read.