This chapter shows how one of the authors, Linnea Bodén, worked collaboratively with a group of children to explore their experiences with brainwave recordings which entailed wearing an electroencephalogram (EEG) cap. Inspired by new materialist and posthumanist emergent forms of inquiry, the children and the researcher together made their own EEG caps. The collaborative exploratory construction of EEG caps and other accessories shows how the children’s individual and different interests were closely tied to each of their worldly (extra)ordinary ways of understanding the EEG caps and the testing itself. The chapter argues that to investigate children’s experinces taking part in research, we need more and emergent kinds of research methodologies. It was necessary to include all of the various relations that the children had with the EEG caps and the testing practice.