what grammatical errors are in this paragraph?

I've been giving my future career a lot of thought and now decided that I could best put my technical skills to use by becoming an educator. As a teacher, my students should be able to expect lessons with immediate feedback for her answers. The problem is that the increasing size of classes are making such goals much difficulter than ever. That's why I plan to program the lessons myself in the C++ language (as learned from professor Duong).

Question

what grammatical errors are in this paragraph?

I've been giving my future career a lot of thought and now decided that I could best put my technical skills to use by becoming an educator. As a teacher, my students should be able to expect lessons with immediate feedback for her answers. The problem is that the increasing size of classes are making such goals much difficulter than ever. That's why I plan to program the lessons myself in the C++ language (as learned from professor Duong).

anonymous · Answer

i've been giving
are making