Crucially, learning is about teachers’ practice too. It is about ‘making a difference’ (Frost, 2006): ‘contributions to knowledge are manifest in … professional practice’ (Frost 2014: 3). But it is not a one-way process - that is, practice is not simply the observable activities and procedures undertaken by teachers and directed by teachers’ knowledge. This would be to see knowledge as a collection of authoritative propositions that are constructed from a vantage point outside practice and used to direct practice; it would be to see knowledge as an instrument to solve problems. Instead, in our view, practice is an interconnected aspect of learning. The relationship between practice on the one hand and knowledge on the other is one of duality: it is a two-way process in which knowledge is used, developed and constructed as practice is enacted, with each affecting the other through an ongoing process of reciprocal influence. (EFFeCT paper)