I went to a new college in the same city for my upper grades. Once there, I started to miss my friends. But the teachers there are good and they do their best. Some of them are former students from my college. To my American ear, it sounds strange to talk about the "upper grades" of a college. High school and elementary school have grades (first grade, second grade, etc.), but not colleges (which to us are like universities and have "classes" rather than grades). However, this usage may vary from country to country. In the last sentence, I cannot tell to which college you refer. Is it the new or the old?