This week we worked on pulse width modulation, PWM, and motors. Pulse width modulation is used to get an output from analog. The output is created by turning the pin off and on very quickly so as to show a change in voltage. The motor requires its own source of power due to the limitations of the Arduino unit. The servo we worked on in class and is shown working by the change in angle of the piece of cardboard on the servo end.
Servos can be used to move an object physically and often do not require their own source of power to run. You need to be careful that everything is correctly in place on the breadboard or you can make a short very easily.