Learn about theremins at: https://en.wikipedia.org/wiki/Theremin
A light dependent resistor or LDR is a light controlled variable resistor. The resistance of a LDR decreases with increasing light intensity. However on the idIoTware shield, the LDR is wired such that with a higher light intensity we get a higher Analog Voltage on Pin A3.
The theremin is a musical instrument that makes spacey sounds as you move your hand near it by responding to changes in capacitance.
In this example we are going to use LDR sensor to make weird spacey sounds. When we wave our hand over the LDR the light intensity changes. This data is then captured by Arduino through a voltage divider. We set the frequency according to the light value by using a map and tone functions in the Arduino IDE to generate specific frequency.
Once you upload the code, test the theremin by waving your hand up and down over the sensor. You will hear different sets of tones.
No more connecting LEDs to breadboard and messy wiring. With the idIoTware shield the sky's the limit.