is an internationally recognized academic and teacher trainer in the field of English Language Teaching (ELT). Thornbury is also the series editor for the Cambridge Handbooks for Language Teachers,[5] and the author of many academic papers on language teaching. His 'A-Z of ELT' blog[6] is one of the most influential and well-visited blogs in the field of ELT.

He is a popular ELT author, practitioner and trainer.  He has trained teachers and offered seminars all over the world. A writer of both course material and methodology, he is the author of methodology titles including How to Teach English‏‎, The Practice of English Language Teaching and How To Teach Writing. He also writes Graded Readers‏‎.

was a Soviet psychologist, best known for his work on psychological development in children and creating the framework known as cultural-historical activity theory. The Zone of Proximal Development: Vygotsky introduced the concept of the ZPD which refers to the gap between a child's current level of development and the level they are capable of reaching with tools provided by others with more knowledge.

Piaget’s (1936, 1950) theory of cognitive development explains how a child constructs a mental model of the world. He disagreed with the idea that intelligence was a fixed trait, and regarded cognitive development as a process which occurs due to biological maturation and interaction with the environment.