You have to come up with a way to send data from your laptop/cellphone to your Arduino. With the following constraints and requirements :

    Use parts from your arduino kit
    You can use other parts commonly found in consumer electronics (earphones, microphones etc)
    No use of bluetooth, RF , FM, wifi or any such wireless technologies
    No USB Communication

The demo must be as follows :

    Enter a number between 0 and 255 in a programme on your laptop or your phone.
    The number should then be transferred over to the arduino using a system that you design ( with the above constraints )
    The arduino should somehow indicate the number that has been transferred using led’s/sound/motors/etc.


(If you are thinking on how to do it, look at all the sensors in your kit : photocell, microphone from your cellphone headset etc. Think of how you can use those to receive data from your computer/cellphone)