Come on guys, this question isn't all that difficult. How about a first test in a class which took you by suprise and you did poorly on? Then you could talk about how you adjusted your study skills to fit the particular class and did well in the class overall. Or maybe how you once forgot about a meeting with a group to do a class project, followed up with saying that it taught you the importance of scheduling, and how your agenda book is now chained to your ankle and color coded. They don't want to know about the times you've messed up and didn't fix it, they want to know how you react to making mistakes.