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Ross Morrison McGill founded @TeacherToolkit in 2007 and is widely recognised as one of the leading influencers in education in the UK and across the world. In 2015, he was named among The Sunday Times/Debrett’s 500 Most Influential People in Britain for his impact on…
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Are teachers unknowingly limiting student achievement?
This blog revisits the original 1968 Pygmalion study and asks what it means for teachers today. The original research suggested that teacher expectations can shape student performance, even influencing measurable IQ gains.
Groundbreaking research
In 1968, Rosenthal and Jacobson published Pygmalion in the Classroom – a foundational study in classroom psychology and teacher expectation research.
Conducted in a California elementary school, they told teachers that a random group of students (n = 320 / see table 1) were about to experience a significant “intellectual growth spurt.”
In reality, the children were selected at random, and the test they used – the “Harvard Test of Inflected Acquisition” – didn’t exist.
It’s a piece of research I still share on my teacher training travels, professionally discovered in 2010.
What the Pygmalion Effect revealed
At the end of the academic year, students in the experimental group gained an average of +12.2 IQ points, compared to +8.4 in the control group. Younger students (Grades 1 and 2) showed the most dramatic increases – some by 27 points or more. The idea that a teacher’s belief could shift measurable IQ has shaped decades of research into expectations and self–fulfilling prophecy.
This became known as the Pygmalion Effect – where internalised teacher expectations shape student performance.
High expectations in the classroom
The Pygmalion study was groundbreaking because it exposed a subtle truth: it’s not just what teachers say, but what they believe that matters. It highlighted how belief quietly shapes behaviour – and how that behaviour influences student success.
Subsequent studies have offered mixed results, something I will share in another blog post update this week. In middle-class schools, the same IQ gains weren’t replicated. Other studies found that older students – or those already known to their teachers – didn’t respond in the same way. Yet one finding remains consistent: When teachers believe in a student’s potential, they unconsciously offer more challenge, more warmth, and more wait time. The effect is strongest when students are:
- New to the school or class
- In early primary years
- Lacking a fixed reputation
- Part of a marginalised or under-served group.
Belief matters – but classroom habits communicate expectations best.
What should teachers do?
Use specific, actionable feedback that expects growth. Praise the process, not just the outcome. Avoid labelling students “low ability”, “middle set”, or “just average” – terms that can quietly cap what a student believes they can achieve. Instead, design your lessons around the idea that every student can improve:
- Use warm-but-strict routines that treat all students as capable learners
- Structure questioning so that everyone is asked high-level questions – not just the confident few
- Give feedback that expects improvement – even for SEND and EAL students
- Model challenge: show that errors are part of learning, not proof of fixed ability
In department or whole-school CPD, encourage teams to reflect on where low expectations might be silently embedded in practice – not because teachers don’t care, but because unconscious bias is real.
Reflection questions for teachers:
- How often do teachers use prior data to set expectations, rather than to inform planning?
- Are students in bottom sets given stretch tasks and not just scaffolding?
- Do teachers expect excellence from SEND or EAL learners – or just compliance?
- How are expectations communicated through tone, wait time and body language?
- Are “middle track” students quietly overlooked?
- Do new students in a class receive a fresh start, or inherit a reputation?
- How do school leaders model high expectations in feedback to staff?
- Is challenge evident in every lesson, or only in observed ones?
- Are “growth spurters” always the same children?
- What professional development supports teachers in recognising their own bias?
The research concludes:
When teachers expected that certain children would show greater intellectual development, those children did show greater intellectual development!”
