Setup: Stretch: This is very dangerous because if for some reason the throw is on you throwing side, behind you, and you have your glove side on the bag it will be hard to turn across your body. With the age group of your players and the throwing ability of them I would suggest you teach them to always use the throwing side foot on the bag and to not stretch until thhey know where the ball is going. Here is a very good website to help with firstbase fundamentals:QCBaseball - Firstbase