Have all of the children on Team A face Team B’s Goal. And likewise, have all of the children on Team B face Team A’s goal. Say to the kids, “You are now facing the goal you want to put the ball in”. That may sound goofy but, when the team is split up on the various lines of the Foosball field they can get confused.
Continue to explain, “You may move back and forth on your line but, you must always keep at least one foot on it. This means you won’t be able to pass someone else on your line. So spread out and be ready to kick the ball when it comes near you.” It’s important that the kids know they shouldn’t pass each other on their lines. Otherwise, you’ll get some of the more aggressive children running up and down their line, doing all of the playing and not letting the other kids do anything.
Now, start some peppy music, roll the ball between the two center lines and play Foosball!
The kids will want to switch places. That’s fine. I had the best luck keeping this under control by becoming the Human Foosball position broker. Kaitlin would ask me if she could switch positions with Mark. I would ask Mark if he would like to switch places with Kaitlin. If both said “yes” then I would have them switch. This might sound like a pain but, it only take 5 seconds, keeps the kids happy and the game organized.