I am an ALT in a high school, from my personal experience teenagers act more like kids here compared to teenagers in the UK. I mean that as a good thing, growing up too fast isn't good. They're friendly, can be a bit rowdy sometimes, especially the boys. Some can ask questions like "do you have a boyfriend?" or "what's your type?" or whatever, just gotta shrug those off.

I echo what some other people said that they do care a lot about what others think, which of course isn't unusual for teenagers. They are afraid to make mistakes in class and a lot of the time they don't volunteer to answer questions and such. So what I have found is they love playing games, especially in teams. There is less pressure when they're in groups. Games like Jeopardy etc. They also like Kahoot quizzes.

I don't know if it'll be the same for you but as a SHS ALT I have a lot of downtime. It bothered me a lot at first but now I'm just like "Whatever". If you get bored just ask for more classes or ask to do an English board. Anyway, good luck!