If you play sports, make a classification of different sports, you can divide the classification of sports into outdoor and indoor sports. If you like nature, make a classification of animals or fauna and flora. If you follow fashion and keep up with all the new things in fashion, then you can make a classification of different kinds of clothes, hairstyles or even fashion accessories.
So, as you can see, there are a huge number of topics for classification. Also, the choice of theme is up to you. If you're not sure if your topic is a good one, ask your instructor's opinion. If you know what you want to write about, and your professor approved the topic, then you can start gathering information for writing a research paper or ask cheap essay writing service uk
for help. Read various books and journals, make your own observations, and ask different people what they think about it.