In order to gain success we have to push through our fears of failure. As an extended jumpstart we are to draw something we are afraid of. The reason is that as artists, we are creators, who are in control. Your fears can't harm you if you are creating a controlled environment for them. You can even make them silly.
The point is that students are being taught that many of the things we feared when we were small we no longer fear because we learned to gain control of those things in our lives. Such as, if you fear the dark, when you get older you simply turn on the light switch. The light switch we are using in our classes is our minds.