What topic would people find interesting? That’s always subjective and it depends on the audience.
In a class presentation though, more people are concerned about your speaking ability than the topic choice. Pick something you’re passionate about and your abilities will shine.
If you want a start though, I’d suggest thinking about the following:
Can you overturn a way of thinking? Breaking misconceptions, especially ones people haven’t heard of is really engaging. For example, using gift cards. Not a lot of people use them, and it’s free money!
Is there something popular to talk about? That depends where you are in the world or the trends, but you could talk about the rise of Korean music in the USA as an example.
Talk about yourself. You’re interesting, and you might find that as you are putting your presentation together.
There are other ideas provided in the other answers, but really you should put some thought into the topics you like. That’s going to be interesting in a class.