We describe the system design of "Smart Kindergarten", a smart problem solving environment for early childhood education. Two crucial building blocks that make up Smart Kindergarten are iBadge, a lightweight power-aware sensor-instrumented badge, and Sylph, a sensor middleware infrastructure. Equipped with sensors, radio, and DSP, iBadge has been designed to be worn by kids and teachers to unobtrusively capture the interaction between the kids and their surroundings. The captured data is then wirelessly transmitted to Sylph, a middleware infrastructure, which provides means of accessing the data in coherent and user-friendly manner. In this paper, we present the design challenges of iBadge and Sylph and our efforts in integrating these two systems.