Using the IR Sensor and Two External LEDs, when there is no object detected the green LED should be on and the red is off. When an object is detected the green LED is off and the red starts blinking every 300 milliseconds.
Note: there is no ir sensor in fritzing, so i used a similar component.
Using three pushbuttons and one buzzer. Make a simple piano that gives a different tone for each button press.
using a potentiometer to control the brightness of an LED.