Touch (knock) sensor with Piezo

If you want to make a simple touch sensor but you don't have the fancy ones around you can also use a piezo element, which come with a lot of basic arduino starter sets. 
 What you need: 
 
 
 
 
 piezo element 
 
 
 breadboard
   
 
 
 resistor 1 M ohm 
 
 
 
 
 
 piece of paper tape 
 
 
 
 
 some male/male jumper wires 
 
 
 
 
 
 This video explains it all. To make the input visual, open the serial Monitor from the Tools menu.