Over the past few years, researchers have been exploring possibilities for how embedded sensors can free children from traditional interaction strategies with keyboards and mice. In this paper, we consider sensing-based interactions from a child's perspective. That is, how children decide to handle sensor data and affect state changes in their environment. We will present this in the context of our research on physical interactive storytelling environments for children. The system architecture will be presented as well as an empirical study of the technology's use with 18 children, ages 5-6. We will discuss the challenges and opportunities for kindergarten children to become designers of their own sensing-based interactions. UMIACS-TR-2003-16 HCIL-TR-2003-05