I listened to two talks at the recent Sounds-Write Symposium that got me thinking about the needs of older learners: Dr Tim Mills Keynote, ‘What Happens when You Miss the Phonics Boat?’ – A Research Study, and Dr Rebecca Sutherland’s talk on the Decoding Threshold: Pioneering Research on Reading’s Hidden Hurdle.

This blogpost is an attempt to pull together some of the key threads from their talks. I hope you enjoy it. Let me know what you think in the comments. Here it goes!

Reading is a gateway to academic success and lifelong learning, yet many older students in upper primary and secondary schools still struggle with literacy, even after passing early reading assessments like the Year 1 Phonics Screening Check. In England, approximately 18% of 15-year-olds lack minimum literacy proficiency (National Literacy Trust), impacting their ability to engage with the curriculum and succeed in life. Educators often focus on improving fluency (reading smoothly and quickly) and comprehension (understanding text) for these students, assuming their foundational skills are secure. However, recent research reveals that many of these learners have gaps in decoding—the ability to translate written words into spoken language—which hinders their reading progress. Two pivotal studies, one by Dr. Timothy Mills and another by the ETS Research Institute in collaboration with Reading Reimagined, demonstrate that teaching decoding skills to older learners is critical for addressing literacy difficulties, far surpassing the benefits of focusing solely on fluency and comprehension. This blogpost synthesises their findings to highlight why decoding should be a priority and offers practical guidance for educators.

The nature of reading difficulties in older learners

Older students, particularly those in Key Stage 2 (Years 3-6) and beyond, often face reading challenges despite appearing competent in early assessments. These difficulties manifest as slow, laboured reading, poor fluency, and struggles with comprehension, particularly when tackling complex, grade-level texts. The root cause is often incomplete decoding skills, especially in handling polysyllabic words, morphology (understanding word parts like prefixes and suffixes), and syntax (sentence structure). For example, Dr. Mills found that 60-70% of Year 5 pupils in the high-deprivation schools in his study lacked comprehensive knowledge of the phonics code, even though they had passed the Year 1 Phonics Screening Check. Similarly, the ETS research notes that only about one-third of students in upper elementary and middle school can read grade-level text independently, pointing to a systemic failure in addressing foundational skills like decoding.

These deficits have significant consequences. Students who cannot decode efficiently expend cognitive effort on word recognition, leaving little capacity for understanding meaning. This creates a cycle of frustration, where students may avoid decoding unfamiliar words or rely on ineffective strategies like guessing, further stunting their reading growth. All of this is well documented in the literature. In his article ‘Individual Differences in the Acquisition of Literacy, Professor Keith Stanovich points out that ‘[s]low , capacity-draining word-recoghnition processes require cognitive resources that should be allocated to higher-level processes of text integration and comprehension.’ As a result, developing readers become demoralised as unrewarded reading experiences multiply’. The ETS study identifies a “decoding threshold” (a score of 225 on the ReadBasix assessment), below which students struggle to progress in vocabulary, sentence processing, and comprehension, underscoring the critical role of decoding in literacy development.

Evidence from research

Dr. Tim Mills’s study on systematic phonics Instruction

In a 2024 study published in the International Journal of Teaching and Learning Sciences, Dr. Tim Mills investigated whether Year 5 pupils (aged 9–11) who do not present as struggling readers but have decoding deficits can improve through systematic phonics instruction. Conducted across four schools in high-deprivation areas of South East London, the study involved 125 pupils. The intervention group received thrice-weekly, 30-minute phonics sessions using the Sounds-Write program, a linguistic phonics approach emphasizing speech-to-print, for 3.5 terms. The comparison group received no additional phonics instruction, continuing with standard reading lessons.

The results were compelling:

• Decoding Skills: The intervention group’s mean score on the Bryant Test of Basic Decoding Skills increased from 38 to 46, with 54% achieving full marks post-intervention, compared to only 9% in the comparison group (mean score from 38 to 42).
• Reading Fluency: The intervention group’s words-read-per-minute rose from 104 to 130, with 71% reading fluently by the study’s end, compared to 50% in the comparison group. The study found that substantial knowledge of simple and complex phonics codes was sufficient for fluency, with polysyllabic decoding less critical.
• Reading Comprehension: The intervention group’s mean comprehension score on the Hodder Progression in Reading Assessment (PiRA) increased from 93 to 105, significantly outperforming the comparison group’s rise from 94 to 98. In Key Stage 2 National Curriculum Tests, 83% of the intervention group achieved the expected standard, compared to 56% in the comparison group.
• Word Recognition and Spelling: Strong correlations were found between decoding and word recognition (r_s = .828) and between decoding and spelling (r_s = .787). The intervention group’s spelling scores on Key Stage 2 tests were notably higher (mean of nearly 15 vs. 11 for the comparison group).

These findings challenge earlier assumptions, such as those cited by Ehri (2004) and the Education Endowment Foundation, that phonics is less effective for older learners. Dr. Mills’s study shows that systematic phonics instruction can address decoding deficits, leading to significant improvements in fluency, comprehension, and spelling.

ETS ReadBasix research on the Decoding Threshold

The ETS Research Institute, in collaboration with Reading Reimagined and the Advanced Education Research and Development Fund (AERDF), conducted studies to explore the decoding threshold and its impact on reading difficulties among students in grades 3-12. Their research identified a critical decoding proficiency level (a score of 225 on the ReadBasix assessment) below which students struggle to make progress in reading. Key findings include:

• Decoding Threshold Impact: Students scoring below 225 on the ReadBasix scale showed slower progress in vocabulary, sentence processing, and comprehension, confirming that decoding deficits limit overall reading development.
• Decoding Behavior: A second study found that students with poor decoding skills spent less time attempting to decode unfamiliar words and relied less on sound-based strategies (e.g., phonological recoding), indicating avoidance or difficulty with the decoding process.
• Prevalence of Issues: Only about one-third of students in upper elementary and middle school can read grade-level text independently, highlighting a widespread need for decoding support.

The ETS ReadBasix assessment, a web-based tool for grades 3-12, includes six subtests (Word Recognition & Decoding, Vocabulary, Morphology, Sentence Processing, Reading Efficiency, and Reading Comprehension) to identify specific reading weaknesses. The research emphasizes the need for ongoing decoding assessment and instruction beyond third grade, as many schools stop evaluating word recognition after this point.

Why decoding matters more than fluency and comprehension alone

Focusing solely on fluency and comprehension often fails to address the root causes of reading difficulties in older learners. Fluency relies on automatic word recognition, which depends on strong decoding skills. Without efficient decoding, students read slowly, stumble over unfamiliar words, and struggle to maintain the flow needed for comprehension. Similarly, comprehension requires accurate word identification to access meaning, and weak decoding diverts cognitive resources from understanding to word recognition.

In their ‘Studies of Expertise from Psychological perspectives, Feltovich et al, highlight the importance of practice: ‘Research on the effects of practice has found that the character of cognitive operations changes after only a couple of hours on a typical laboratory task. Operations that are initially slow, serial, and demand conscious attention become fast, less deliberate, and can run in parallel with other processes.’ In terms of learning to read and write effectively, decoding knowledge and skills need to be very well established in the primary years.

Dr. Mills’ study illustrates this interconnectedness: pupils who improved their decoding through phonics instruction saw significant gains in fluency (from 104 to 130 words per minute) and comprehension (PiRA scores from 93 to 105). The ETS research further supports this, showing that students below the decoding threshold are constrained in their ability to progress in other reading subskills, such as vocabulary and sentence processing. These findings suggest that decoding is not just a foundational skill but a continuous necessity for reading development.

Some researchers, like Timothy Shanahan, argue that phonics has limited impact on comprehension for older learners, emphasising vocabulary or background knowledge instead (Journal of Adolescent & Adult Literacy). However, the evidence from Mills and ETS leans toward decoding as a critical starting point. By addressing decoding deficits, educators can replace ineffective compensatory strategies (e.g, guessing words) with sound-based approaches, paving the way for improved fluency and comprehension.

Practical implications for educators

To effectively support older learners with literacy difficulties, educators should adopt the following strategies:

1. Assessing Decoding: Use tools like the Bryant Test, which assesses decoding through 50 pseudo words (covering initial, extended, and polysyllabic codes), or the ETS ReadBasix assessment to identify students below the decoding threshold. These quick, targeted tests provide clear insights into decoding weaknesses.
2. Systematic Phonics Instruction: Implement programs like Sounds-Write, which emphasizes speech-to-print and includes both decoding and encoding (spelling). This approach is adaptable for older learners and avoids childish elements by framing lessons as spelling activities.
3. Integrate Decoding into Broader Reading Instruction: Incorporate decoding practice into fluency and comprehension lessons, such as reading texts with unfamiliar multisyllabic words to reinforce skills.
4. Targeted Interventions: Offer small-group or one-on-one phonics sessions for students with identified decoding deficits, focusing on Extended and Polysyllabic Code knowledge.
5. Teacher Training: Equip upper primary and secondary teachers with phonics training to understand its importance and deliver effective instruction. This is crucial, as many educators lack knowledge and experience in teaching phonics beyond early years.

These strategies align with the findings of both studies, which advocate a forensic approach to diagnosing and addressing reading difficulties. By prioritising decoding, schools can ensure students have the foundational skills needed to access complex texts and succeed academically.

Addressing the controversy

The role of phonics for older learners is not without debate. Some educators and researchers argue that phonics is less relevant for older students, who may benefit more from strategies targeting vocabulary, background knowledge, or test-taking skills. However, the evidence from Dr. Mills’ study and the ETS research suggests otherwise. The significant improvements in fluency and comprehension following phonics instruction indicate that decoding deficits are a primary barrier for many older learners. While vocabulary and background knowledge are important, they are less effective if students cannot decode the words they encounter. By addressing decoding first, educators can create a solid foundation for other reading skills to build upon.

Conclusion

The research by Dr. Tim Mills and the ETS Research Institute provides a compelling case for prioritising decoding skills in older learners with literacy difficulties. Far from being a skill reserved for early years, decoding is a critical foundation for fluent reading and comprehension, even in upper primary and secondary education. By using targeted assessments like the Bryant Test and ETS ReadBasix, and implementing systematic phonics programs like Sounds-Write, educators can address decoding deficits and unlock significant improvements in reading outcomes. Focusing solely on fluency and comprehension without addressing decoding is like building a house on a shaky foundation—it may hold for a while, but it will eventually falter. As we work to close the literacy gap and empower all students to succeed, a renewed emphasis on decoding offers a proven, evidence-based path forward.

Key statistics on literacy challenges

Statistic	Source	Year	Description
18% of 15-year-olds lack minimum literacy proficiency	National Literacy Trust	2022	Highlights reading challenges in older students
Only one-third of students in upper elementary/middle school read grade-level text independently	ETS Research Institute	n.d.	Indicates widespread decoding deficits
83% of intervention group achieved expected standard in KS2 reading	Mills (2024)	2024	Compared to 56% in comparison group, showing phonics impact
60-70% of Year 5 pupils lacked comprehensive phonics code knowledge	Mills (2024)	2024	Despite passing Year 1 Phonics Screening Check

References

1. Mills, T. (2024).Can Older Pupils Who Do Not Present as Struggling Readers Improve Their Basic Decoding Skills Through Systematic Phonics Instruction, and What Effect Does This Have on Their Reading Fluency and Comprehension? International Journal of Teaching and Learning Sciences.
2. ETS Research Institute, Reading Reimagined, & AERDF. (n.d.).Research Report: Decoding Threshold in ReadBasix Highlights.