In this exercise you will use a whistle to create agility challenges. There are unlimited variations as you will quickly realize. Just use a little imagination. You will also need a fairly flat running surface and a line to run along. Just have the junior athlete run on one side of the line and when the parent or coach blows a whistle, the junior simply changes to running on the other side of the line. One variation is to perform the same drill with side shuffles as well. And, you can also perform the same shuffle drill with 180-degree turns and switching sides of the line at the same time. Again, this is a terrific agility-building as well as reaction-and-response drill that will improve performance in many movement sports.