Coaching in a group setting sometimes requires that you give technique work that everyone is able to do.
Why Do It:
The most common (and important) technique in swimming is streamline. The best way to maximize the streamline is with a good underwater dolphin. Having all swimmers perform this with a pre-determined mark, or distance off the wall, allows coaches to see who needs the most help.
How to Do It:
1. First, instruct all the swimmers in the group of where they’re required to get to on every push off.
2. As each wave of swimmers leaves the wall, watch to see who has the most trouble in making it to that mark.
3. Based on the momentum of the swimmers, and the distance, both coaches and swimmers should be able to better determine if their "mark" should be closer, or farther, than the original set distance.
4) Obviously, no "marks" should be past 15 meters. Also consider that not all athletes will make it to that distance effectively for training.
How to Do It Really Well (the Fine Points):
Practicing underwater dolphins is always a good idea. When you do it in a group setting it makes the coach’s job easier because it’s easier to determine which swimmers need the most coaching. You make the coach’s job even easier by setting the bar a little bit low. When a minimum performance is required on something as simple as walls, those who can’t keep up become as noticeable as an injured fish to a hungry shark. Those are the swimmers who require the most attention and help from the coach, and who can show the most improvement by maximizing this skill.