Addressing teachers

I was sitting in the Bulgarian classroom and needed help. So I called for my teacher Helene. When I said her name I noticed that I got strange looks from the Bulgarian students, but why?

1. Because I had a strange voice?
2. My teacher had a strange name?
3. Because I didn’t call my teacher by their last name?
4. I’m not supposed to call for help?

Explanations

1. If you look at someone who has a strange voice, you are not very polite person.
2. Helene isn’t a strange name.
3. Yes, it’s inappropriate to call your teacher by their first name. In Bulgaria you call them by their last name.
4. Teachers are there to help.