This article draws on data from a project on children's playground games and rhymes in the new media age. One objective of the project was to examine the relationship between traditional playground games and children's media cultures. As part of the project, two ethnographic studies of primary playgrounds took place in two schools, one in the north and one in the south of England, over a two-year period. Children in both schools were active participants in the research process. They informed the research design and ongoing data collection through children's panels and children were involved in data collection through the use of video cameras, interviews and diaries. This article reflects on a number of critical issues that are raised when considering the nature of the cultural knowledge constructed by the children as they identify the signifying practices of their play and its relationship with media culture. The concept of knowledge brokering is used as a heuristic device to analyse the nature of children's contribution in participatory research studies. (Contains 3 notes.)