Scrimmages

Kids don't come to practices to stand around and pass the ball to each other. They come to play!
Absolutely, every practice session should have a scrimmage at the end. In fact, using the promise of the scirmmage, I get the kids to practice harder, pay more attention and not waste too much time. Usually I tell them: "If you guys waste time and not listen, we won't have enough time at the end for the scrimmage". It's a great incentive to get them to listen.
And ofcourse, you have to stand by your promise.
Divide up the teams into two (almos equal forces). Here I would advise you that you should not be so strict as try to make the teams strengths exactly equal. It's impossible. During the course of the play if you see too much imbalance where the ball does not get out of one team's penalty box, take a couple of good players from the better team and have them switch to the other team. It quickly balances the scale.
In any case the kids will get their training out of these scrimmages one way or another, whether they are mostly defending or attacking.

A couple of important points:

1. Make sure you have "pennies" to give out to one team so that kids know who is on which team. Sometimes kids have trouble putting the pennies on. Help them out.

2. Many times kids ask you to put them on the other team because their friends are playing there! It's fine. Go with it. In fact sometimes you actually want kids who play well with each other to be on one team so you can have them practice passing to each other.

3. Make sure you allow about 30 minutes of scrimmage at every practice session. By the time you divide up the teams and get the kids going, another 5 minutes is gone!

4. Run along with the kids in the field and cheer them on. "Thomas: go for the ball...that ball is yours...don't stand around", etc. Don't let anyone stand around. Ask players to move into open space.

5. Don't let one goalkeeper stand in goal all the time. All players need to play even goalkeepers. Switch goalkeepers every 10 minutes or so.

6. Make it a happy scrimmage and encourage passing as much as possible.