In the research literature several positions concerning the role played by metacognition in adaptive strategy choice can be distinguished. While many authors adhere so-called metacognitive models of strategy choice and strategy change, others have questioned the extent to which metacognitive factors are associated with strategy choice and task performance and have proposed alternative theoretical frameworks wherein strategy choices are described in terms of associative models. In the present article we report data coming from a larger research project on the development of children's numerosity judgement strategies and skills. The experimental task involved judging numerosities of colored blocks presented in a rectangular grid. Participants were 59 second grade and 50 sixth grade children, whose strategic performance dataobtained by means of a systematic analysis of their response-time patterns -were compared with interview data collected at the end of the experiment. The major result of this comparison is that not only the children from the oldest age group, but also the children from the youngest age group showed clear evidence of metacognitive awareness and understanding of different aspects of their strategic performance.
Different views on the relationship between metacognition, strategy use and performanceAs documented in numerous older and recent studies in the domain of (mathematics) education, children and adults often use multiple strategies on a given task. This variability is not just present from one person to another or from one item to another, but also appears within a single person or item (Siegler, 1996). In line with this general finding, strategy development cannot be appropriately described as the replacement of one strategy with another. Rather, it should be considered as a complex developmental process whereby the appearance