Short answer: hearing a fluent, expressive narrator read while a child follows the words is one of the best-supported ways to support reading fluency — and that's exactly what read-along is. But it's worth being precise about what the research shows and what it doesn't. Reading along is powerful as a model of fluent reading and as a way to give kids access to stories above their level. It isn't a replacement for kids reading themselves, and the science on highlighting specifically is still young. Here's the honest picture — with the studies.
First, what is reading fluency?
Fluency is reading accurately, at a comfortable pace, and with expression (prosody — the rhythm and intonation of natural speech). Reading Rockets calls fluency "the bridge between word recognition and comprehension": once reading the words becomes automatic, a child's attention is freed to actually understand the story — the classic automaticity idea from LaBerge & Samuels (1974). Kids who read haltingly spend so much effort decoding that little is left for meaning.
The strongest finding: a fluent model helps
The clearest evidence is for modeling. The National Reading Panel found that guided oral reading — reading with guidance and feedback — reliably improves word recognition, fluency, and comprehension. A meta-analysis by Therrien (2004) found that hearing a fluent model of a passage before reading it produced bigger fluency gains than reading it cold — and adult models beat peer models. Children's prosody, in turn, develops toward the adult patterns they hear (Miller & Schwanenflugel, 2008). This is the heart of read-along: a professional narrator models fluent, expressive reading, and kids absorb the rhythm.
What about following the words while you listen?
Reading-while-listening — eyes on the text, ears on a narrator — has encouraging evidence. Ninth-grade language learners who read silently with audiobooks read significantly faster while keeping comprehension steady (Tusmagambet, 2020). "Listening passage preview" shows up across fluency research as a reliable way to lift reading rate and accuracy (Steinle, Stevens & Vaughn, 2021). The honest caveat: gains in rate and accuracy don't automatically become comprehension gains, especially for older struggling readers — so reading along is a support for reading, not a substitute.
Does the highlighting itself help?
Here we'll be candid: the evidence for synchronized highlighting specifically (the word lighting up as it's spoken) is promising but still small. In one experiment, a synchronized "karaoke" style helped sixth-graders remember word meanings better than an unsynced version (Gerbier et al., 2015) — though a follow-up found older children benefited more than younger ones. A small pilot with dyslexic readers found synchronized highlighting made text easier to track (Ikeshita et al., 2018; just seven children). So highlighting appears to help kids map speech to print, stay on the line, and stay engaged. We won't claim it's a proven fluency cure — the studies are early and modest.
For struggling and dyslexic readers: access is the real win
It's tempting to say audio support "raises reading scores" for kids who struggle. The best-designed study we found doesn't support that: when secondary students with dyslexia read with professional audio, it changed how they read and how long they spent — but it didn't boost comprehension test scores (Knoop-van Campen et al., 2021). The genuine, defensible benefit is access: audio lets a child experience a story above their independent decoding level and lowers the cognitive load of grinding through every word — so they stay in the book.
How we built Sherwood around this
That's why Sherwood works the way it does: real human narrators (not AI voices) who model fluent, expressive reading; word-by-word read-along so kids connect the spoken word to the printed one; captions on every title; and dyslexia-friendly fonts across the captions, ebooks, and read-alongs. Read-along here is meant to do the two things the research supports best — model fluent reading, and open up stories kids couldn't yet read alone — alongside their own reading, not instead of it. (More on the mechanism in Why Reading Along Works.)
The honest bottom line
Reading along, done well, is a research-aligned way to support fluency — strongest as a model of fluent, expressive reading and as a bridge to books a child couldn't yet read alone. It works best paired with kids reading themselves. Anyone promising that highlighting or audiobooks alone will "fix" reading is getting ahead of the evidence.
Sources: Reading Rockets; National Reading Panel (2000); LaBerge & Samuels (1974); Therrien (2004); Miller & Schwanenflugel (2008); Tusmagambet (2020); Steinle, Stevens & Vaughn (2021); Gerbier et al. (2015, 2018); Ikeshita et al. (2018); Knoop-van Campen et al. (2021).