You need to know where your students truly come from. If possible, you should visit their homes. You should talk to their parents or guardians. Try to find out what skills and hobbies their parents or guardians have, and then find meaningful contributions using their talents, skills and hobbies. Understand that however these students act or seem, they all started out in life as innocent and excited about learning as our own children.
Kids are kids. They are pretty much the same everywhere, and good teachers--regardless of where they teach--will reach those kids. Teachers must first and foremost like children. They must understand them and work toward that understanding...not all are the two-parent, three meals a day kids. I love the reference above to Erin Gruwell's book. She is an inspiration.
I tend to think that the labels of "urban" or "rural" might be more of red herrings than anything else. All teachers should know the area in which they are teaching. They should know about what conditions and factors are in that are which effect the learning process. When entering into any setting, teachers cannot pretend that the outside world does not bear any impact in their daily instruction and pedagogy. This means that understanding the environment in which one teaches and in which one's students live helps to make for quality and effective teaching. I would tend to stray from the idea that "urban" schools have a different skill set than other areas because I think this moves us into a realm where no one would like to be present. When trying to determine what a teacher "needs to know" about a particular area, I would say that teachers should try to know everything about a certain area that impacts the lives of their students and, thus, the effectiveness of instruction.
I'm not sure if you are asking for advice when seeking a position there or if you are looking for qualities of teachers. Being a freshman, I think you are not looking for a job yet and would think you may have an assignment requiring qualities...
Having taught in several school district types, I would have to encourage the following knowledge set:
1. All students can learn, but are daily impacted by greater stresses than we require of them. In an urban district, you may see a much higher level of poverty which means many students are helping their parent(s) fend for the dollars that pay the bills. Students in urban districts may be dealing with greater language barriers, gang affiliations, impoverished living situations, domestic violence amid other potential problems.
2. Students are not likely to be engaged in learning, thus you will have to build rapport and find means that encourage them to think. You have to use what they are interested in to connect it to the curriculum and skills you are required to teach. Many students with issues of great concern outside of school will psychologically carry that into the classroom.
3. Your resources are likely to be small, and your exterior support base is less than in suburban or rural district from parents, mentors and coaches.
Read Erin Gruwell's book, "Teach with your Heart". She addresses her experience in Long Beach with inner city high school kids... the tough kids.
Your question seems like one that you might want to turn into a Discussion Board. The list of what a teacher needs to know to teach in an urban school district is almost endless. I'll mention one important element.
A teacher needs to know how to preteach behavior. Along with this comes a knowledge of social skills and social skills vocabulary. Much negative behavior can be prevented by teaching the behaviors that are expected before the behaviors become issues. Reacting to negative behavior is not nearly as effective as preventing it. Reacting is also much more difficult mentally and emotionally for a teacher than preteaching is.
For instance, students should be taught immediately to wait for a pause in a conversation before trying to enter it. In other words, they should be taught to avoid interrupting. A teacher has to handle it when a student rudely interrupts, but much of the tendency students have to interrupt in order to say something or in order to get attention can be eliminated by preteaching that social skill.
Preteaching is one of a thousand things a teacher needs to know, but I hope it helps.
Especially in an urban setting, teachers should be very familiar with the local laws of that area including any local ordinances or other little-known laws, and also the policies of the school. After that it is primarily following the local customs and traditions of the area and staying within the laws and policies of the school. Everything else should be received from your department head or immediate supervisor, and/or school administration. Always present yourself in a professional manner and decorum, and you should have no problem fitting into any situation.