This paper describes a context-specific electronic design and prototyping approach in an innovative project course at Carnegie Mellon. We built a sensing and notification wearable computing platform, called eWatch, for context-aware computing. eWatch senses user activities and provides them with urgent notifications. An accelerometer and microphone provide inputs to a model of user interruptibility levels. A vibration motor for tactile feedback and two ultra bright LEDs for visual feedback provide user notification through different vibration patterns and colors. User studies identified appropriate notification schemes for mobile and office settings. Bluetooth communication connects the eWatch to a PDA or desktop computer for sensor data analysis and notification.