Writing a controversial essay isn't something a tutor will explicitly tell you to do. It's something you have to decide on yourself whilst fitting it to the task at hand. For example, if a tutor assigns an argumentative paper you may choose controversial essay topics to help enhance your argument. This is how to access the higher grades. Ideally, you should opt for these topics as often as possible as it demonstrates maturity through the ability to handle a particularly sensitive set of issues.