The aim of this paper is to describe how tools used in action research can promote learning in relation to Vygotsky’s concept of the zone of proximal development (zpd). In the study, Vygotsky’s (2001) theory of the zone of proximal development was used to describe how knowledge development can be manifested in a work of change. The data production took place in a school improvement project where fifty teachers participated over a period of three years. Tools for data production, and at the same time tools for learning, were: facilitation, shadowing and individual log book writing. The tools were initially analysed from three aspects: as used individually, as used in pairs or in a group, and in relation to the zone of proximal development. The responses were divided into confirmations and challenges. Although the participants expressed a need for challenges, they were in practice more prone to confirm one another. This gap showed the importance of analysing and openly talking about the difference between confirmation and challenge in zpd. In the joint analysis work, differences were elucidated between using tools outside zpd and learning through tools within zpd. Knowledge was developed in both situations but at different levels of reflection. In relation to zpd, the importance of colleagues was emphasised. In her/his competence development, a teacher is dependent on one or several critical friends (cf Handal, 2007) to be challenged as a knowledge developer. Giving response proved more difficult in virtual meetings than in physical meetings.