For our first big project, I decided to make a raincoat the reacted to light and water. Being from California and going to school in Massachusetts has been a big transition and the sudden downpours can catch you unaware. This raincoat has built in light and water sensors so when it gets dark the raincoat lights up so the wearer will be visible in the dark, and when it gets wet, a warning beep sounds so the wearer can head for cover.
Step 1: Raincoat
Step 2: Circuitry
The circuits I used were based on the digram below which I got from this board. For my water sensor I ended up using a 1M resistor instead of 10k.
For the light sensor, I based my circuit off of this SparkFun inventor's guide for the light sensor on page 24.