I have coached numerous sports for kids in this age range and it is difficult to get their attention. I use hand clapping... When the kids start talking over others, playing around, not gather where they should or just are generally not paying attention I start clapping hard and fast claps... Kids that still aren't listening are told to sit out the next drill, although I have only had to do that twice over the years and one of those was my own son, lol I went to a cub scout meeting when my son first joined and was watching the leaders try to organize the kids for a game... It was chaos!! The leaders were holding up bunny ears to trying to get the kids to listen... After a minute or so I started clapping and barking out orders... The kids were lined up in no time So I have found this to be a good technique for me... Of course you have to have a voice that can bark over your claps