If you have a Makey Makey you will love this project! just connect 5 bananas to the arrow keys and the space bar using the crocodile clips included in the Makey Makey package. Then order the bananas left arrow, up arrow, right arrow, down arrow, space bar. Now play your piano by touching earth and tapping the bananas. Also if you don't have a makey makey you can just touch the keys.
