Teach the Figure 4
The first thing a baserunner must learn is to fold the back leg under his lead leg in the form of the number 4. Help your players fold one leg behind the other while standing. Then show them how to fold the one leg under the other while sitting. Then have each take quick little two- or three-step slides on a low-friction surface, folding his leg under and landing on his folded knee, the top part of his lead leg and his backside. Make sure the runner does not turn on his side and slide on his hip.
Keep Hands in the Air
As your players progress toward full-speed slides, make sure they keep their hands high and contact the ground with only their lower bodies. Players risk finger, hand and wrist injuries by reaching down with their hands to cushion a slide into the ground.
Stress Proper Sliding Distance
Teach a player to start her slide close enough to the base to reach it before she loses momentum. For the average-size player, that is about 10 feet. The player must not start her slide too late; that could cause her to jam her leg awkwardly into the base during midslide. Clearly mark the proper slide starting point during your sliding practice.
Keep Lead Leg Bent
Instruct every player to keep his lead sliding leg slightly bent as it hits the bag. This reduces the risk of knee injury upon contact with the bag. This technique also helps more advanced runners pop up onto the base into ready position to keep running, should there be a loose ball.
Teach the Hook Slide
Once players have mastered the straight-in slide, teach them to use similar mechanics on the hook slide. Instruct the players to slide toward the right or left of the base, then reach back and grab the base. As each player becomes more advanced, have a coach or volunteer assume a fielding position that forces the runner to read the situation and hook slide one way or the other as she comes into the base.