Questioning & Discussion 4 interventions

How to read these numbers

• "Months of progress" is a teacher-friendly shorthand from the EEF Toolkit. It is not directly comparable across studies — different meta-analyses use different baselines, age groups, and outcome measures. Treat it as a magnitude indicator, not a precise prediction.
• Cohen's d is the standardised effect size used in the original meta-analyses. d ≈ 0.40 is Hattie's "hinge point" — the average effect of a year of schooling. Higher = larger relative effect, but context matters more than the number.
• Effect sizes are averages. A skill that shows large average effects can still produce small or negative effects in a specific classroom. Use these as a starting point for professional judgment, not a substitute for it.
• Sources are dated. Where multiple meta-analyses exist, we lead with the most recent quality study and cross-reference EEF where available.
• Implementation cost (Low / Medium / High) is a practical signal — not an exact science — of what your school needs to invest in teacher time, training, and structural changes to actually run the intervention well. It is the editorial team's reading of what the intervention typically requires in practice. Use it to gauge whether something is straightforward to introduce or a larger undertaking — not as a budget figure.
• Some interventions are also priced in £ (UK) by the EEF Toolkit. For monetary cost data, see the EEF Teaching & Learning Toolkit.
• Colour bands signal calibration, not value. An intervention in the "below typical" band is not "bad" — it means the intervention's average effect is below the typical effect of a year of schooling. That can still be appropriate for specific contexts the average does not capture.