Sami has done another great summary of research. Enjoy!
Kim, Y.K. & Wagner, R.K. (2015). Text (oral) reading fluency as a construct in reading development: an
investigation of its mediating role for children from grades 1 to 4. Scientific Studies of Reading, 19, 224–242. DOI: 10.1080/10888438.2015.1007375.
A student’s ability to interpret strings of letters as words (word fluency) and their skills in understanding spoken information (language comprehension) are both very important in retaining and making inferences based on written information (reading comprehension). However, recent research suggests that, in order for these skills to be connected, students must demonstrate mastery of text fluency: the ability to efficiently read words not as lists but as related concepts and to understand their meaning when presented as a passage. It has been hypothesized that, after achieving sufficient skill levels in word fluency, this text fluency will begin to be developed with some help from language comprehension, and that text fluency soon becomes the factor which links literacy skills together and paves the way for greater understanding. In order to test this hypothesis and to determine how relationships between text fluency, word fluency, reading comprehension, and listening comprehension change over time, Kim and Wagner (2015) tracked the progress of a group of students from first through fourth grade, and the results were promising!
In general, relationships among all of the different components were positive – as skills in one area increased, so too did skills in others. Listening comprehension and reading comprehension retained an increasingly strong relationship throughout all four years of the study. The correlation between word fluency and text fluency, in contrast, weakened over time. A possible explanation for this is the fact that the strength of the relationship between reading comprehension and text fluency increased as reading comprehension’s relationship with word fluency decreased. This supports the hypothesis that word fluency starts as a critical component of developing reading comprehension skills, but once word fluency has been developed to a sufficient degree (around second grade, in the students tested in this study), text fluency eventually surpasses word fluency as the most pivotal component of reading comprehension. However, the relationship between text fluency and listening comprehension, which is weak at first, strengthens over time, thus indicating that language skills are necessary in order to achieve this increase of abilities in text fluency. Further research is needed, potentially in areas regarding learning disabilities or English as a second language, but increasing oral skill and text fluency exercises in the classroom could nevertheless be a worthwhile area of investment!