Motor 
In class I created a motor by using only a battery, a wire, a magnet, and some paper clips and rubber bands.  A motor is something that turns electrical energy into mechanical energy.  This is done when a current carrying wire experiences a change in its magnetic field, this is what the magnet is for.  When the magnetic field changes a torque is created.  This torque causes a rotation and it is that rotation that is used to do things.