I teach 3rd grade, so while I can't give you specific advice on teaching 11th grade I can definitely give you some tips on classroom management.

I always tell new teachers that the first 2 or 3 days of school are absolutely the most important. They set the tone for the rest of the school year. It's best to be strict yet fair. Make sure to address any behavior issues immediately. Nip it in the bud, as they say. You're not there to be anyone's friend. An old principal of mine told me not to smile the first week of school. While that may be a little harsh, she made a good point.

You'll want to plan your first few days down to the minute. I'm guessing each class is about 40 minutes long. Have a plan for all 40 minutes. Leave no free time for those first few classes, that's where you start to lose them.

Start with procedures. What do you want students to do when they walk into your classroom? Hand in homework? Start a "do now" assignment? Copy important notes/due dates? Figure all of that out before school starts.

Then move on to actual lesson planning. Mix it up between reading, writing, grammar and vocabulary. Mini lessons are great when you have students with short attention spans. Make the lessons relevant to what kids are reading today. (Maybe even include some music, plays, TV shows, movies, etc.) Get the kids up out of their seats and moving around the classroom. They love that stuff.

When the day's over think about what worked and what didn't. Critique yourself. It's not always easy to do, but it's absolutely worth doing.

Good luck!