Stretching Forward: What Does Acceleration Really Mean in Practice?
Hattie’s Visible Learning Effect Size Series – #17 Acceleration – Effect Size 0.68
To note: John Hattie’s Visible Learning research brings together over 1,500 meta-analyses, covering more than 90,000 studies and millions of students. Its aim is to identify what works best in education by measuring impact using ‘effect size’. In this context, an effect size of 0.4 is considered average progress over a year. Anything above 0.6 is seen as highly impactful. This blog is part of a 20-post series exploring the top-ranked influences in Hattie’s Visible Learning research, with a focus on practical strategies teachers can use to make a meaningful difference.
When we hear “acceleration,” we often think of skipping ahead. But Hattie’s research shows that acceleration is not about rushing. It is about moving learning forward with precision and purpose, providing stretch when students are ready for it, not when we feel the pressure to push.
Hattie places Acceleration at an effect size of 0.68, but he is clear that this only works when students have already mastered prior content and are well supported to succeed in more advanced work. It is not about missing foundations. It is about building on them.
What Do We Mean by Acceleration?
Acceleration in Hattie’s research refers to strategies that enable students to access content above their chronological or year level, not by skipping content, but by teaching it earlier, or more deeply, when students are ready.
This can include:
• Compacting curriculum to avoid repetition
• Teaching more advanced content earlier in the sequence
• Providing enrichment that mirrors the complexity of higher-level tasks
• Re-grouping students based on readiness, not just age
It differs from simple differentiation because it involves rethinking the pace and pitch of progression, not just the task within a shared objective.
Enrichment broadens learning at the same level. Acceleration moves learning forward to new content, once the previous has been mastered.
Why It Matters
When done well, acceleration:
• Keeps high-attaining students engaged and challenged
• Builds self-efficacy through stretch and success
• Signals to learners that their ability to progress is not fixed to year groups
• Increases opportunity, particularly for students who may be ahead in one subject but not all
It also reduces boredom from unnecessary repetition, and prevents students from coasting through content they have already mastered. Acceleration makes learning responsive, not restrictive.
Practical Strategies for Effective Acceleration
1. Use Diagnostic Pre-Assessment Before Each UniT - Identify who already has mastery, and design entry points that allow them to move forward sooner.
2. Offer Tiered Tasks With Extension Built In - Provide anchor tasks for all students, with pathways that lead into higher-level applications, not just more work.
3. Rethink Grouping Flexibly - Use fluid, needs-based groups that allow for acceleration in one unit or strand, rather than fixed ‘top groups’.
Avoid language like “top set” or “gifted group, acceleration is about opportunity, not labels. Grouping should remain flexible, evidence-informed, and responsive to progress, not locked to perception.
4. Integrate Advanced Vocabulary and Concepts EarlieR - Don’t save rich language or abstract ideas for the end of the year. Introduce them early with support and modelling.
5. Use Challenge-Oriented Feedback - Instead of “good work,” ask, “What’s your next step?” or “Where could you take this further?” Feedback should move learning on.
Quick Wins for This Week
• Look at the first task in your next unit. Can you add a pre-check to see who’s already secure?
• In your next lesson, plan one extension question that applies learning in a new context
• Review your groupings. Are they based on evidence, or habit?
• Add one advanced term or concept into your next model or explanation, with scaffolding
Try This
At the start of your next unit, ask:
“Who already has the foundations to stretch forward?”
Then ask yourself:
“What support would it take to let them accelerate — not just move faster, but go deeper?”
The goal is not more. It is meaningful challenge.
Challenges and Considerations
Acceleration is not for all students, all the time. It must be based on secure understanding of prior content. Rushing too soon can leave gaps.
It also requires planning and confidence. Teachers need access to diagnostic tools, adaptable curriculum maps, and support from leaders to adjust pacing.
Students should feel supported in the process and, where appropriate, consulted on their readiness and confidence to accelerate. Ownership matters.
Acceleration should not be confused with streaming. Groupings must remain flexible and responsive, not fixed or limiting.
Reflections for Teachers
• Who in your class is ready for deeper challenge, and how do you know?
• Are your extension tasks stretching learning, or just adding complexity?
• Do your assessments and planning allow for movement, or just pace control?
Reflections for Leaders
• Does your curriculum allow room for acceleration, or is it locked to year-level pacing?
• Are staff trained and supported to assess readiness and adapt their planning?
• Is your timetable and grouping structure flexible enough to allow for progression beyond year-group norms?
Further Reading and Resources
• Hattie Ranking: 256 Influences Related To Achievement
https://visible-learning.org/hattie-ranking-influences-effect-sizes-learning-achievement/
A comprehensive list of factors affecting student achievement, including acceleration programs with an effect size of 0.68.
• Acceleration – National Association for Gifted Children (NAGC)
https://nagc.org/page/acceleration
Overview of acceleration practices and guidelines for implementation in educational settings.
Research Connections
• Hattie, J. (2009) – Visible Learning
Identifies acceleration as a high-impact practice, particularly when student readiness and support are in place.
• Colangelo, N., Assouline, S., & Gross, M. (2004) – A Nation Deceived
A key report highlighting that acceleration is often underused, despite strong evidence of its effectiveness.
• Tomlinson, C. A. (2001) – How to Differentiate Instruction in Mixed Ability Classrooms
Emphasises that acceleration must include access, support, and rich challenge — not just moving ahead faster.
Visible Learning Blog Series
1. Stronger Together: How Collective Teacher Efficacy Unlocks Student Potential (1.57)
2. Students Knowing Themselves: How Self-Reported Grades Support Progress (1.33)
3. Judging Potential: The Power of Teacher Estimates of Achievement (1.29)
4. Supporting Every Learner: How Response to Intervention Changes Trajectories (1.29)
5. Teaching for Thinking: Why Piagetian Programs Make a Difference (1.28)
6. From Misconception to Mastery: How Conceptual Change Programs Support Deep Learning (0.99)
7. Knowing Where to Start: Why Understanding Prior Knowledge Enables Effective Teaching (0.94)
8. Making It Stick: Why Connecting New Learning to What Students Already Know Matters (0.93)
9. Belief Before Progress: Why Self-Efficacy Is a Game-Changer for Learning (0.92)
10. The Trust to Teach: Why Teacher Credibility Drives Student Engagement (0.90)
11. Micro-Teaching: How Short Reflections Make a Big Difference (0.88)
12. Classroom Discussion: Dialogue as a Driver of Thinking (0.82)
13. Targeted Support: What Works for Learners with Additional Needs (0.77)
14. Relationships That Matter: How Teacher–Student Connection Fuels Learning (0.72)
15. Revisiting and Remembering: Why Spaced Practice Outperforms Cramming (0.71)
16. Learning to Learn: Why Does Teaching Thinking Matter So Much? (0.69)
17. Stretching Forward: What Does Acceleration Really Mean in Practice? (0.68) — You are here
18. Calm and Clear: How Classroom Management Enables Progress
19. Word Power: Why Vocabulary Programs Widen Access
20. Read It Again: How Repeated Reading Builds Fluency and Confidence
Next up: Calm and Clear — exploring how classroom management, when built on clarity and consistency, creates the conditions for great teaching and learning.