Here a list of relevant exercises, and these include the recommendations given previously.
On the fun side, the kids love the novelty and physical part of these exercises. You just show them and they do them with vigor. I would not recommend doing this sequence before a slow-paced activity like rehearsing your free kick plays or some other boring tactical activity that is not high intensity because the psychological direction will be wrong - you will go up hill and then try to go to lower intensity, and that kills mental focus. Practices should be fairly monotonic in intensity - from less intensity to more intensity.
1. 1v1 Pass and Chase
Two players 2 yards apart, one with ball. Player with ball knocks it 10 yards and pursues. Partner sprints to ball with passer in pursuit, gets ball, runs 3 quick steps with ball, stops. Exercise repeats as new player on ball passes 10 yards into space in new direction for partner (original passer) to collect. 60 seconds.
2. 1v1 Pushing in Space
Partners pushing with shoulders and hips. Players try to hold ground and gain ground. Great leg development, balance, and natural influence toward lowering center of gravity. Kids will be surprise. "All we have to do is push ?" When you say "yes", they will laugh, but really get into it. 60 seconds.
3. 1v1 Pushing to Cone
Partners with cone. One defends cone by shoulder charging and shielding to hold opponent from cone, the other tries to push in close enough to the cone to touch it with a foot tap. Attacking player can switch shoulder and change directions often, forcing player defending cone to turn quickly and charge with other shoulder. One point per tap. Change roles after 60 seconds. Players keep score. Ask who won.
4. 1v1 Pushing to Cone with Ball - No Tackling Partners with ball and cone. One defends cone by shoulder charging and shielding to hold opponent from cone. The other partner tries to push close enough to the cone to touch it with a foot tap, but has to carry ball on opposite foot, usually dragging it along with the sole on top of the foot. Player defending cone may not touch attacker's ball. One point per cone tap. Change roles after 60 seconds. Players keep score. Ask who won.
5. 1v1 Pushing to Cone with Ball - Tackling Allowed
Same as 4, except player defending cone can try to knock ball away from attacking player to gain time while attacker retrieves ball. Defender is shielding and shoulder charging to protect cone, attacker has to carry and protect ball.
6. 1v1 Pushing to Ball
Partners with ball. Defending player holds ball in a near-stationary position and defends by pushing with shoulder and shielding as attacking player tries to touch ball. One point per tap. Change roles after 60 seconds. Players keep score. Ask who won.
7. 1v1 Shielding Moving Ball
Same as 6, except defending player can move with ball. Ask players with ball not to run away, but to stay in a 5 yard grid and use shielding and turning moves to maintain possession and to protect the ball. Change roles after 60 seconds, players keep score, ask who won.
8. 1v1 Ball Pursuing Ball
Partners, each with ball. Attacker with ball pursues opponents ball, cuts ball and uses all surfaces to try to touch balls together to score point. Defender with ball shields, changes directions, and changes pace within a 5 yard grid. Change roles after 60 seconds. Keep score. Ask who won.
9. 1v1 to Cone
Partners with ball. Attacker with ball tries to beat defender and touch cone with ball to score point. Change roles when goal is scored. Don't allow defending players to passively stand by cone. Award penalty goal to attacker when you see this. Play 60 seconds. Rest a moment, repeat. Players keep score. Ask who won. Rotate to new partners, complete 3 or 4 sequences.
10. 1v1 to Two Cones
Partners with a ball and two cones. Cones on ground about 5 yards apart, depending on age level. Play as in 1v1 to Cone, but can score at either cone. This eliminates cone hanging by defender. Play 60 seconds, repeat. Players keep score. Ask who won. Rotate to new partners.