Equal groups of players at all four corners of the half court ,the first ones have the ball , faced towards the middle of the half court. With the whistle they start dribbling to the middle of the court , then perform a direction changing move then pass the ball to the first of the row.
(reverse , crossover , back , between legs , etc... )

For kids , make them wait in front of the cones while dribbling , then let them to perform the move , not to sacrifise the techniqe .

Improving team harmony and fundamental skills

Tell all players who will perform to start at the same time
Dont forget perform with both hands