School performance data is useful when you treat it like evidence, not a verdict. Most metrics are trying to answer one question: what outcomes did pupils achieve, and how much did they improve relative to their starting point?
This guide explains the measures parents see most often: KS2 outcomes for primary schools, and Attainment 8 and Progress 8 for secondary schools—plus the practical pitfalls that make comparisons misleading if you are not careful.
Key takeaways
- Attainment measures describe outcomes; progress measures describe improvement from a starting point.
- Progress 8 is often the fairest single-number comparison for secondary schools, but you should still check absolute attainment.
- For primary schools, KS2 measures are helpful, but trends and cohort context matter a lot.
In this guide
How to read performance data (without getting misled)
Start by asking what the metric is measuring: attainment (final results) or progress (improvement from a starting point). Progress-style measures are often the fairest way to compare schools with different intakes.
Then check whether a number is part of a trend. One year can move because cohorts are small, curriculum choices changed, or staffing/leadership shifted. Your goal is to understand direction and stability, not chase a single snapshot.
- Use more than one measure: progress + attainment + context.
- Prefer multi-year patterns over one-year spikes.
- Treat tiny cohorts with extra caution (results can swing).
KS2 (primary): what the measures actually mean
KS2 outcomes are reported at the end of Year 6. Reading and maths are tested (SATs) and reported using scaled scores. Writing is teacher assessed.
The most common parent-facing measures include the percentage of pupils meeting the expected standard, the percentage achieving the higher standard, and average scaled scores (especially in reading and maths).
Primary results are still meaningful, but avoid treating them as the only proof of school quality. Small cohorts, pupil mobility, and SEND/disadvantage mix can change outcomes year to year.
- Expected standard: how many pupils hit the benchmark in core subjects.
- Higher standard: how many pupils are well above that benchmark.
- Scaled score: a score designed to be comparable across test versions.
Attainment 8 (secondary): GCSE outcomes across a broad set of subjects
Attainment 8 summarises GCSE outcomes across a basket of subjects. English and maths are double-weighted, then there are slots for EBacc subjects and other approved qualifications.
It is easiest to think of Attainment 8 as “average GCSE points across the basket”. As a rough mental model, a score around 50 is similar to an average grade 5 across the slots (with English and maths counting twice).
Attainment 8 is useful because it tells you what grades pupils actually achieved. But it is not automatically a fair comparison between schools with very different intakes, because it does not adjust for where pupils started.
Progress 8 (secondary): value-added from KS2 to GCSE
Progress 8 compares pupils’ Attainment 8 outcomes to the national outcomes of pupils with similar starting points at KS2. It is designed to answer: how much progress did pupils make from primary to secondary, compared with similar pupils nationally?
A Progress 8 score of 0 means average progress. Positive scores mean above-average progress; negative scores mean below-average progress. As a rule of thumb, +0.5 is roughly half a GCSE grade per subject higher than similar pupils nationally.
Progress 8 is still not perfect: confidence intervals matter (especially for small cohorts), curriculum entry patterns can influence results, and it does not capture everything parents care about (pastoral support, inclusion, wellbeing).
- Look for a positive score with a confidence interval that stays above 0.
- Cross-check with Attainment 8 so you understand absolute outcomes too.
- If Progress 8 is weak, ask what has changed recently (leadership, staffing, curriculum).
How to use these measures when choosing between schools
Use performance data to shortlist and ask better questions—then validate the story with visits, behaviour culture, and how the school supports different learners.
If you are comparing secondaries, start with Progress 8 (fairness) and then check Attainment 8 (absolute grades). If you are comparing primaries, look at KS2 outcomes and (where available) progress-style indicators, then check how consistent results are over time.
Finally, put results in context. Attendance, suspensions, and Ofsted narrative can help you spot whether outcomes are likely to sustain or whether there are warning signs.
A simple plan you can follow
Use this as a lightweight workflow as you shortlist, visit, and decide.
- Decide whether you are comparing primary (KS2) or secondary (Attainment 8/Progress 8).
- Check the latest results, then look for multi-year patterns where possible.
- Use progress-style measures first for fairness, then confirm absolute outcomes.
- Cross-check with Ofsted narrative, attendance, and behaviour culture on visits.
- Shortlist schools that look strong on both data and day-to-day fit for your child.
Practical templates
Use these lists as prompts on open days and when comparing schools side-by-side.
- KS2 expected and higher standard reviewed (primary).
- Attainment 8 reviewed (secondary).
- Progress 8 reviewed with confidence interval (secondary).
- Trends checked over multiple years where available.
- Context checked (attendance, cohort size, demographics).
- Visit questions prepared based on what the data suggests.
- How do you support pupils who start behind in literacy and numeracy?
- How do you stretch high attainers and keep them motivated?
- What has changed recently that might affect results (staffing, curriculum, leadership)?
- How do you use assessment data day-to-day, not just for reporting?
- What does behaviour look like in lessons and how is it kept consistent?
- Comparing schools by attainment only without considering intake.
- Overreacting to one year of results without checking patterns.
- Ignoring confidence intervals and small cohort effects.
- Assuming one metric captures culture, SEND support, or wellbeing.
Use this with Schoolboard
Turn the guide into a shortlist you can compare on the map and school pages.
- Use the map to colour by performance measures and spot local patterns.
- Sort by Attainment 8 or Progress 8 to build a shortlist quickly, then open school pages to sanity-check the details.
- Use guides alongside school cards to understand what each metric means before you decide.