Can you revise this paragraph by combing sentences

My first day of school in america was also my worst nightmare. I woke up early in the morning. My uncle took me to school. I sat in the classroom during the first period and listened. I could not understand what the teacher was talking about. Fifty minutes passed. I saw others walk out of the classroom. I did not know what they were doing. I walked out with them. I still realize that the school system in america was different from that in china. Students in china do not change classrooms every period. The teachers do. Students in america rather than teachers change classrooms. So i went back to the same classroom again. I stayed in that room until noon.

Lunch hour was coming. In china,everybody goes home for lunch. I thought people did the same thing here. I left for home. A school security man stopped me outside the school. He talked to me. I did not know what he was saying. I was frustrated and scared. I wanted to cry. Some of my schoolmates looked at me as if i were an alien. My face turned red. My heart was crying. I hid my tears. A Chinese girl came up and talked to me in Chinese. She told me we had to stay in school until the last period. I did not know she would become my best friend. I did know my worst nightmare had ended.