cheryl, i think it's great that you go to your grands' practices and games. i've had many parents or guardians that just drop off their kids and want to know when to pick them up, or even have to call or text them when to come.
coaches notice that stuff.
develop a good, ass kissing relationship with the coach (little food treats for the team after practices works. not for after games, though. you never know if they'll win or lose, and it's confusing to celebrate after a loss).
then, the real secret is to tell the coaches to watch and study the same cartoons and kiddie shows on tv that their players watch afterschool.
during practices, if you joke around about it and/or imitate the characters or phrases that the cartoons say, the kids are amazed that you know something else from their life and immediately draw better attention to what you're trying to teach them.
a simple trick, but it makes them crush their opponents, er, i mean play their best...