I got the TIP120, diode, DC supply from the shop, and the 12v lamp from RadioShack.I made two silly mistakes in this lab.
Mistake 1: the lamp acts so wired, it lights up sometime, and it didn't do anything sometime. Finally I found that it's because there's no common ground and common power on the both edge sides on the breadboard.
Mistake 2: the lamp lights up immediately and is not controlled by potentiometer. This is because I connected the lamp to the base instead of the collector. The picture on the website has this little mistake.
This is the video with the DC motor:
This is the video with the 12v lamp: