Hattie compared the effect size of many aspects that influence learning outcomes in schools and points out that in education most things work. The question is which strategies and innovations work best and where to concentrate efforts in order to improve student achievement. The Times Educational Supplement described Hattie's meta-study as "teaching's holy grail".
According to Hattie's findings, visible learning occurs when teachers see learning through the eyes of students and help them become their own teachers. Hattie found that the ten most effective influences relating to student achievement are:
- Student self-reporting grades (d= 1.44)
- formative evaluation (d=0.9)
- teacher clarity (d=0.75)
- reciprocal teaching (d=0.74)
- feedback (d=0.73)
- teacher-student relationships (d=0.72)
- meta-cognitive strategies (d=0.69)
- self-verbalisation/ questioning (d=0.64)
- teacher professional development (d=0.62)
- problem-solving teaching (d= 0.61).
Some of the statistical methods used by Hattie have been criticised. Hattie himself admitted that of the two statistics in Visible Learning, one was calculated incorrectly throughout the book.
- Hattie, John (2008). Visible Learning: A Synthesis of Over 800 Meta-Analyses Relating to Achievement. NY: Routledge. p. 392. ISBN 978-0-415-47618-8.
- Mansell, Warwick. "Research reveals teaching's Holy Grail". TES. Retrieved 2013-03-28.
- John Hattie admits that half of the Statistics in Visible Learning are wrong
- Topphol, Arne Kåre. 2011. Kan vi stole på statistikkbruken i utdanningsforskinga? Norsk pedagogisk tidsskrift 06 / 2011. ('Can we rely on the use of statistics in education research? Norwegian journal of paedagogy' in Norwegian)
- An email exchange between John Hattie and members of the Student Committee of the teacher-training programme at the University of Oslo (in English), Response to Hattie's response by Topphol (in English)
- Gardner, Howard (2011). "Making Learning Visible. Children as individual and group learners (Project Zero)". Reggio Children. Giudici, Claudia; Krechevsky, Mara; Rinaldi, Carla. Retrieved 3 August 2016.
- De Florio, Inez (2016). Effective Teaching and Successful Learning. Bridging the Gap between Research and Practice. Cambirdge/New York: Cambridge University Press.