My kids have hit squabbling--bickering about nothing, usually something silly, resulting in tattling.
What Works for Me is a Love and Logic strategy--give them jobs. So on Saturday, as I was trying to get dinner ready and they were arguing about who-knows-what, I had Henry move the laundry (take dry clothes out of dryer and into basket; move wet clothes from washer to dryer; turn on dryer) and Harmony unloaded the dishwasher (she stacked stuff on the counter).
It was a win-win-win situation--they had something productive to do instead of bickering, the argument was dropped, and two chores got done without me having to do it :)
For more ideas, visit Works for me Wednesday at Rocks in my Dryer!