You are right that was also my reaction when I heard the topic of your history lesson, the word "Imperialism" it is very abstract, it is difficult to relate to something, you can't "see or touch" it. I believe many children or even adults will be having problem to explain what they understand under this definition if one asks. The way how you build up your lesson is really good, it interacts and there are many examples that we can apply to nowadays. Unfortunately it is a reality how the world works. People sometimes just do not want to think about that if they live in nice, established environment of Western countries. But I can imagine how it is for those who live in other countries, weaker, without a power. It is a great job a teacher, you are once who influence those young generation, our future. My total respect @hanshotfirst!