Internship at a high school/secondary school?

Hello,

I (male, 15) am in 9th grade at a secondary school in Bavaria, which is why I have to do a mandatory internship this year. Since I want to become a high school teacher one day, I would like to do an internship at a secondary school or at my secondary school.

Is that possible? Have you ever done something like this before?

I dropped down from the high school where I wanted to do an internship to the Realschule because of poor grades. But this year I have a 1.8 average.

I thought that I would only be able to do internships at primary schools, since I would be hanging around with my friends at a high school/secondary school, but a friend said it was okay.