The Touch Sensor gives your robot a sense of touch. 
The Touch Sensor detects when it is being pressed by 
something and when it is released again.
You can use the Touch Sensor to do a lot of things: if a robot 
has a Touch Sensor connected to a leg it can tell how far it has 
moved by counting how many times the Touch Sensor has been 
pressed.
 
The Touch Sensor can also be used to detect if your robot 
bumps into an obstacle and make it react to it.
 
You can also use a Touch Sensor to make your robot act on a 
command. For example, by pressing, or releasing your Touch 
Sensor you can make your robot walk, talk, close a door, or 
turn on your TV. 
 
Test the Touch Sensor and get a fun reaction.  
Connect a Touch Sensor to port 1 of your NXT and 
select the Try-Touch program in the Try Me submenu 
on the NXT’s display.
  
150ppi / 125%