The toughest part to me is graphics. Overall, I have to grasp the chain of function to make an object work(move, pop-up, resize, animate, etc) following the order that I want. When it comes to a large project, I mess up all since the project has to involve many classes and additional .py files, which requires me to organize the order, systemize the loop, and take advantage of classes. So far, I still find it hard, but even after the course, I"ll keep spending my time and my summer to grasp it!