**1. Introduction**

According to the most recent scores from the National Assessment of Educational Progress (NAEP), a significant number of fourth- and eighth-grade students in the United States (U.S.) are failing to read at satisfactory levels [1]. Specifically, 32% of all fourth-grade students were found to be reading below basic levels, demonstrating di fficulties with making simple inferences and finding relevant information to support their understanding of a text. This statistic sees an alarming increase among students identified as having learning disabilities, with 68% of struggling fourth graders reading below basic levels. This is hardly surprising considering that di fficulties with reading are commonplace among students identified with learning disabilities [2].

Chall's stages of reading highlight the importance of oral reading fluency as students' decoding develops. Proficient oral reading fluency is one of the main characteristics identifying children moving from stage 2 (learning to read) where the focus is on rapid decoding of words to stage 3 (reading to learn) where students begin to gain new knowledge and ideas through their reading of increasingly complex texts from a variety of di fferent genres [3]. Based on Chall's model, fourth graders should be entering the reading-to-learn phase (stage 3). However, findings of students reading below basic

levels in the fourth grade on the NAEP sugges<sup>t</sup> that many fourth graders in the U.S. have not entered this phase and are still working to master learning to read. Students' difficulties with oral reading fluency may thus be one factor prohibiting students from progressing to the more advanced stages of reading development [3]. This theoretical proposition is well supported in research conducted among students in the U.S. For instance, Daane, Campbell, Grigg, Goodman, and Oranje examined a subsample of fourth-grade students who took the NAEP reading assessment in 2002 and identified 40% of the sample to be "non-fluent" readers who also scored at or below the basic achievement level on the overall NAEP reading assessment [4]. The negative impact of deficits in oral reading fluency extends to many other school subjects that require students to gain understanding through reading [5], further underscoring the importance of oral reading fluency for reading development. Beyond the U.S. context, the importance of fluency for reading is also evident in that reading curricula standards across different countries and languages cite the achievement of fluency in reading words and texts, typically by grade three, as a curricula goal [6]. Deficits in automaticity in reading have also been found to be associated with children identified as having reading disabilities across a range of languages [7,8].

Therefore, in light of the far-reaching effects of difficulties in reading fluency and that fluency is identified as a crucial building block of reading development [5,9], it is essential that fluency interventions be provided for elementary students demonstrating difficulties in reading [5]. An increase in oral reading fluency skills would allow students to read more complex text at more proficient levels. Thus, this synthesis of research will examine the types of interventions which aim to build the oral reading fluency and their impact on reading outcomes in students with reading difficulties.

#### *1.1. Oral Reading Fluency*

Fluent reading is often conceptualized as being synonymous with three aspects, namely, the ability to read texts with accuracy, appropriate rate, and prosody [10], with the ultimate aim of extracting meaning in reading [11]. The multifaceted nature of fluency and the association between fluency and reading comprehension is well-placed in theory and empirical research [11–14]. For one, how rate and accuracy components in reading fluency facilitate reading comprehension is outlined in the model of automatic processing [15]. According to this model, all individuals have limited cognitive capacity which makes it necessary for readers to develop automaticity in lower-level word recognition skills such as grapheme–phoneme correspondences and phonemic awareness in order to dedicate adequate cognitive resources to higher-order tasks involving comprehension of texts [15]. This ability to develop automaticity in word recognition processes is what often differentiates fluent from dysfluent readers. Dysfluent readers likely find their cognitive attention consumed primarily by decoding as they have to intently and laboriously attend to letters, sound-symbol correspondences, and word recognition. The inability to achieve automaticity in lower-order processing places large demands on working memory, leaving few resources available to negotiate meaning making in texts. Considering the centrality of working memory in facilitating the storage and retrieval of information in texts during the process of reading for comprehension [16,17], non-automaticity in decoding hinders reading comprehension [18].

It has also been suggested that fluency aspects of accuracy and rate mediates the association between decoding and reading comprehension, a postulation that has been empirically supported. Silverman, Speece, Harring, and Ritchey measured the contributions of aspects of decoding comprising phonological awareness, word and nonword reading as well as fluency (measured by speed and accuracy in reading words, sentences, and texts) in reading comprehension, controlling for linguistic comprehension [19]. They found that when fluency aspects were not included in the model, there was a significant relation between decoding and reading comprehension. However, this relation was no longer apparent once fluency was accounted for. In addition, students who were good decoders but non-fluent readers were weaker in reading comprehension as compared to those with strong decoding and fluency skills [19]. The finding in Silverman et al. that good decoders could be further classified as fluent or dysfluent readers also supports that of previous research, suggesting that although there

is a strong association between decoding and fluency [20,21], proficiency in the former does not automatically translate into the latter. Rather, explicit instruction that builds up fluency is necessary to facilitate the transition from being able to recognize words accurately to being able to recognize words both accurately and rapidly [19].

The role of prosody in reading comprehension has also been established, although to a lesser extent than accuracy and rate aspects. Prosody, a frequently overlooked component of oral reading fluency [22], is concerned with reading with expression and is associated with the ability to produce appropriate changes in pitch and stress as well as use appropriate phrasing and intonation [14]. Prosodic elements are suggested to be central components of fluency and reading comprehension because reading words in meaningful phrases allows readers to focus on the ideas in the text and students who read without expression are likely not gaining full meaning of texts [9,23]. Empirical research supports this view. For instance, in a study examining the relationship between prosody and reading comprehension in 80 third-grade students [24], students read aloud a passage which targeted specific characteristics of prosodic reading, including (1) basic declarative sentences thought to elicit a decline in pitch, (2) basic quotes intended to elicit pauses in phrasing, (3) yes/no questions designed to elicit an increase in pitch, and (4) phrase-final commas thought to elicit pauses in phrasing. Findings showed that children who demonstrated greater prosodic awareness, where they showed a decline in pitch in declarative sentences and an ascent in pitch with yes/no questions, had higher reading comprehension scores as those who did not.

#### *1.2. Oral Reading Fluency and Reading Di*ffi*culties*

Increasingly, deficits in reading fluency have been acknowledged as an area in which children with reading disabilities struggle [20,25]. This is evident in that oral reading fluency was added to the federal definition of a specific learning disability through the Individuals with Disabilities Education Improvement Act (IDEA) in 2004 [26]. Scientific studies of reading also support this view. For instance, as evidenced in Daane et al. [4], many students with reading di fficulties were dysfluent readers who read slowly and laboriously. These students often struggled with automatic word recognition and had to stop frequently while reading to sound out words or use structural analysis to look for common syllable types or morphemes [27]. In another study, Rasinski and Padak examined the word recognition, oral reading fluency, and reading comprehension abilities of 604 students in second through sixth grade identified as having reading di fficulties [28]. After collecting data from an informal reading assessment (Ekwall Reading Inventory) and routine assessments given by teachers, Rasinski and Padak concluded that di fficulties with reading speed translated into fluency deficits that negatively impacted reading comprehension [28]. In another recent study, Kang and Shin concluded that an estimated 6% of struggling readers in upper elementary grades exhibited early reading di fficulties related to decoding and fluency [29]. Moreover, when combined with students who had issues with basic reading skills, as well as comprehension, more than half of all struggling readers in upper elementary grades displayed deficits in decoding and fluency skills. Their work emphasized that fluency is, in fact, an essential component of reading comprehension, and that fluency, while it overlaps with decoding, is a separate component that makes unique contributions to reading comprehension.

In light of the evidence suggesting the crucial role fluency plays in reading, especially among children with reading disabilities, researchers have pointed to the importance of interventions targeted at raising students' fluency skills. Specifically, researchers have emphasized the need for interventions to target fluency aspects directly rather than indirectly through other related reading skills such as phonological awareness because interventions of the latter nature alone have not been shown to improve fluency skills [5,12,30]. Researchers have put forth that fluency improvements increase reading comprehension among struggling readers indirectly by freeing up limited working memory resources to be used in higher-order processes in reading [15,31,32]. This explanation is tenable considering that research has shown that children with reading di fficulties often exhibit working memory deficits, see [33] for a review.

*Educ. Sci.* **2020**, *10*, 52

However, fluency instruction is often absent from elementary school reading curriculum today, possibly because classroom teachers are rarely provided with any training on instructional strategies to promote oral reading fluency [34]. This lack of attention to fluency in instruction and the consideration that fluency is a skill that has been identified to be di fficult to build up points to the importance of examining the e fficacy of direct interventions of fluency [35,36]. In addition, considering the close association between fluency and reading comprehension, examining the e fficacy of fluency interventions on reading comprehension in addition to fluency outcomes is necessary. In general, previous syntheses and meta-analyses that have examined children with reading disabilities have shown oral reading fluency interventions to be e ffective in improving fluency and/or comprehension outcomes in school-aged children [37–39]. Across these reviews, researchers have also highlighted the importance of considering characteristics including type of intervention, type of interventionist (adult vs. peer), number of times texts were read in the interventions, pre-instructional support, corrective feedback, and number of elements included in interventions in order to assess intervention effectiveness [37–39], although these have not been systematically examined among children with reading di fficulties across reviews. For instance, the systematic review conducted by Therrien found considerable e ffect sizes associated with fluency interventions on fluency and comprehension outcomes for students with and without learning disabilities (LD) and highlighted that interventions that were conducted by an adult typically yielded greater e ffect sizes as compared to those mediated by peers [39]. However, the review focused solely on repeated reading interventions and did not consider the e ffects of other types of interventions. In addition, the characteristics of interventions and their e ffectiveness on reading outcomes for LD children specifically were not discussed. Similarly, only repeated reading interventions were examined in a more recent meta-analysis conducted by Lee and Yoon and the effects of interventions on fluency outcomes only were examined. Transfer e ffects of fluency to reading comprehension outcomes were not examined [37]. Furthermore, although the review conducted by Chard et al. discussed in detail intervention characteristics related to di fferent fluency interventions and the e ffects of interventions on both fluency and comprehension outcomes, e ffect sizes across studies reviewed were not reported [38]. In addition, the number of studies reviewed pertaining to the di fferent intervention characteristics were very small, making it di fficult to draw definite conclusions from these studies. Finally, in the most recent synthesis by Stevens et al. [40], single-case studies figured as the majority which the authors noted could impose limits on the generalizability of findings.

#### *1.3. The Current Study*

In light of these gaps, this paper seeks to systematically examine the e ffects of oral reading fluency interventions on elementary students (i.e., first through fifth grade) identified as having reading di fficulties across a range of experimental studies conducted in school settings. Specifically, we addressed the following objectives: (1) whether oral reading fluency interventions increase the oral reading fluency (i.e., accuracy, rate, and prosody) and reading comprehension of elementary students identified as having reading di fficulties, and (2) the characteristics of e ffective interventions that facilitate these reading outcomes.

In addition to providing a more updated examination of the e ffectiveness of fluency interventions, the current review builds on previous syntheses [37–40] in several ways. First, we expanded our examination of types of fluency interventions to include that other than repeated reading. Second, we examined the magnitude of intervention e ffects on both fluency and comprehension outcomes within the same synthesis to examine the local and transfer e ffects of interventions, respectively, and compared the magnitude of e ffects of interventions on both types of outcomes. Third, our present study only reviewed group-design studies, following Stevens et al.'s point about limitations on generalization of findings with single-case designs [40]. Furthermore, we only included studies that had a control group in order to control for quality of study design and to allow for more definite conclusions to be made about the e ffectiveness of fluency interventions. Finally, although previous syntheses did not examine whether group size influenced the e ffectiveness of interventions, we consider this variable in our present study. This is because intervention studies pertaining to di fferent reading constructs have yielded di fferent findings regarding optimal group size for interventions [41,42]. Thus, it is necessary to examine whether this variable influences intervention outcomes.
