What factor most likely disrupts an entering second-grade student's reading fluency?

The factor of lack of phonics knowledge significantly impacts a second-grade student's reading fluency. Phonics involves understanding the relationship between letters and sounds, which is essential for decoding words while reading. When students struggle with phonics, they may have difficulty blending sounds together or recognizing common patterns in words, leading to choppy or hesitant reading. This hampers their ability to read smoothly and with appropriate pace, which is a critical component of reading fluency.

While vocabulary, comprehension, and reading habits are all important aspects of reading development, they tend to influence reading ability in more advanced ways. Insufficient vocabulary can hinder understanding but may not directly affect the ability to read fluently. Similarly, poor comprehension skills can affect how well a student understands text, but if they cannot decode the words fluently due to phonics issues, comprehension becomes irrelevant. Inconsistent reading habits might lead to lower overall engagement with text, but lack of phonics knowledge is more foundational to achieving the level of fluency needed in second grade.