I listened to the lecture well. 🙂 It was good because I could easily understand polymorphism. Polymorphism.. It's easy to say, but the concept is more difficult than I thought, and applying it is even more difficult, but I think you explained it easily and made the practice problems at an appropriate level. And what I liked the most was how the code goes into memory when you write it, and how you reference and retrieve the values. It was good because I was able to gain more than when I studied alone by reading a book..! I'll wait for the next lecture while reviewing it..! 🙂