Read this excerpt from little brother and answer the following questions in complete sentences using proper grammar and punctuation:

after a heated classroom discussion with his substitute teacher, marcus is sent to the assistant principal's office.

i went fast to mr benson's office. cameras filmed me as i went. my gait was recorded. the arphids in my student id broadcast my identity to sensors in the hallway. it was like being in jail.

"close the door, marcus," mr benson said. he turned his screen around so that i could see the video feed from the social studies classroom. he'd been watching.

"what do you have to say for yourself? "

"that wasn't teaching, it was propaganda. she told us that the constitution didn't matter! "

"no, she said it wasn't religious doctrine. and you attacked her like some kind of fundamentalist, proving her point. marcus, you of all people should understand that everything changed when the bridge was bombed. your friend darryl—"

"don't you say a word about him," i said, the anger bubbling over. "you're not fit to talk about him. yeah, i understand that everything's different now. we used to be a free country. now we're not."

"marcus, do you know what 'zero-tolerance' means? "

i backed down. he could expel me for "threatening behavior." it was supposed to be used against kids who tried to intimidate their teachers. but of course he wouldn't have any compunction about using it on me.

"yes," i said. "i know what it means."

"i think you owe me an apology," he said.

i looked at him. he was barely suppressing his sadistic smile. a part of me wanted to grovel. it wanted to beg for his forgiveness for all my shame. i tamped that part down and decided that i would rather get kicked out than apologize.

in three to five sentences, summarize the conflict marcus is facing in this excerpt.