Be ready and be quick. Your players need to be able to move quickly a short distance, usually to their left or right. This requires pushing off quickly on the opposite foot. By pushing off on the opposite foot, this reduces the tendency of the player to lead with their strong foot, which would require one additional step at least 50% of the time.

Get there in a hurry. Not that an opponent would ever get behind your defensemen, but just in case, you should teach them how to quickly turn and run to catch up. This involves planting the foot nearest the opponent and then swinging the other leg in front of the body as they turn and sprint towards the ball.

Marking. This involves the defensemen guarding the opponent to prevent them from making effective shots-on-goal. When marking an opponent, the defender should always remain with their assigned opponent, keeping themselves between the ball and the goal. Younger players will want to go around a ‘shielding’ opponent to steal the ball, leaving an unimpeded path to the goal for the opponent.

Tackling. Not related at all to the same skill in football. But it is the same thing as stealing. Teaching your player to tackle the ball effectively requires that they be fully aware of the ball at all times, especially in relation to the opponent. Effective tackling is mostly a matter of timing, which will be difficult for younger players. Things for the defensemen to watch out for:

If the opponent loses control or pushes the ball too far ahead, be prepared to take it and pass it down the field.

Be sure that you have backup when trying to make a tackle near midfield.

Approach an opponent with their body position sideways to the opponent with the chest pointed away from the touchlines. This keeps the opponent from simply ‘punching’ the ball between the defenders’ legs. Go for the ball, not the player.

Learn respect for the opponents’ speed and quickness.