Stress. 
It can be a killer, literally, but what can we do? 
There are as many stressbusters as there are people, and what you do to relieve it is up to you, just keep it positive. The thing is, what do we do to help our kids to get over the stress of school/home/atheltics/clubs/etc?  The best solution is to be there for them, establish good working relationships and treat every moment as a teachable one.  We often forget that our kids are under even more pressures than we are, especially at this critical age.  Consider what they're going through:
1) A very different environment than what they've seen before.
     Most of our kids are used to self-contained classrooms with one teacher and one group of peers.  for many, others outside this group are 'strangers' unless they happen to live nearby.  Most are only seen on a bus or in the halls.  Now, though, all are thrown together and new relationships are developing.  It can be rough, and there are going to be conflicts.  Keep encouraging working groups and shuffle the mix so that there are as many combinations as possible so that all get to know one another.  Too, the shuffle in the halls from class-to-class can be an issue.  Teach them how to do it quickly and in good order with established locker times, enforce timing,and keep your own cool.  Modling this behavior will teach them more than coersion could.  At my school we spent time each day with this, and there has been a great payoff.
2) Choices are being offered.
     For the first time for many, the choices of good behavior vs. poor behavior, what clubs to join, whom to sit with at lunch, and how to spend class time are offered.  They're used to more structure, so provide it for them.  Spend a minute each day to reinforce your policies, reward the good stuff, and teach them how to make better choices.
3) They're growing up.
     There are all kinds of psychological and biological things happening just now.  All this can lead to what a friend refers to as "the screaming troop of monkeys in the brain".  Teaching kids how to filter out the noise and focus on the important stuff (I find that "there's a time for everything" adage works), and don't forget to keep in touch with your guidance people.  They can provide help, advice, etc.  Model efficiency, organization, and focus, then help them to these ends.

We're moving on in time, and, undoubtedly, curriculum issues, committees, and other things are piling up, but if we model how to handle our stress, the kids will learn from us how to deal with theirs.

Off to the classroom!