Related but not a dupe. One of my Japanese teachers often explains things in a difficult to understand way, or because she uses a lot of Japanese quite quickly, sometimes with constructions we haven't quite covered. I often don't understand the tasks that are set. Usually I can ask, but there's a point where I feel like I'm annoying my classmates, and there are a few lessons where I've walked out and everyone was confused. It's just this teacher, the other four communicate very well in general. I'm not going to say anything yet, but the question is: what should I do if this is a persistent issue? What is the most polite and appropriate way to approach her out of hours and tell her that I am struggling to understand her.
I was in a similar position as your classmates in my language course. I'll describe the situation so you can "step into my shoes" and see how it looks from the other side. Hopefully, this will help you understand your situation a bit more.
I'm fluent in spoken Chinese, but being illiterate in would prevent me from passing the equivalency exam, so I took the Intro 101 course with most of the class not being able to speak any Chinese.
Our professor was a grad student originally from China. Her English was acceptable as she was a native Chinese speaker, and she had only come to the US after college.
I had no issues with other students (the class was probably ~15 people) asking for directions to be repeated again more slowly.
Reason? Because, from experience, I know languages are hard to learn. I may be fluent in Chinese, but if I were to take a French class, I'd be in the same boat.
The other students in your class should be able to recognize that you are a new learner. Now, leaving the class might not have been the best response, but you can't change that now. I would recommend not leaving class in the future. That's counter-productive.
Have you tried talking to the other students or asking them for help? I'm sure they're willing to help you learn Japanese as well. Certainly, if they already know the material, they might not even want to be in a rush to go through all the material.
I guess a final concrete example is in order.
If you were an English teacher with a college mastery of English, and teaching a 1st grade English class, would you be annoyed when the 1th graders asked 1st grade English questions?
You can always ask for the task instructions in English, as it's an introductory class she probably won't mind repeating it in English. If the problem persists you might want to just privately say you have some problems understanding her, and explain a bit why, some of your peers might have similar issues.
(I have been in three introductory language courses and had such an issue as well)
If the other students are also having difficulties, speak with another member of staff who is a friend of hers - indicate that your group is having trouble keeping up with the lesson plan, and ask that staff member if you should approach your teacher directly. Often word will get back about you asking for advice.
If it's just you, then ask your teacher if there is tutorial or support lessons you could do to improve your phrasing/parsing skills. Often this is the best way, as you asking for help is polite and acceptable - as opposed to complaining. Often your teacher will then consider if her phrasing or speed is a little too fast and will slightly adjust their teaching method because often if one person can't keep up then two others are only just managing.
And if you truly can't follow the phrasing or meaning of what you're asked then you do need some extra remedial work.
It's normal. Many of us have been there. The sooner you act the better. Just be prepared to be passed through a lot of hoops or have to run with it yourself, as in the end you are the one responsible for your life/learning.