The Convention on the Rights of the Child foregrounds the right to participate. Contributing to decision-making on matters concerning children's lives is fundamental to rights education. This paper discusses ethical and methodological considerations of children's rights-based epistemology, arguing that children are competent to reflect upon and exercise their participation rights. The present study explores 4/5-year-old children's perspectives on play in an Australian early childhood education service. It aims to identify ethical spaces in research involving children. The findings address children's participation choices; including conditional assent, dissent, and their influence on the research. These outcomes are important because (a) little is known about the ways children choose to participate, and (b) they raise questions about the realisation of children's participation rights. This paper concludes by examining the implications for research that acknowledges children's demonstration of their participation rights in physical, creative, and social-emotional spaces. [Paper presented at the International Conference on Human Rights Education (ICHRE) (9th, Sydney, Australia, 2018).]