Take a look at this submission from John, one of my subscribers. A great idea for [tag]baseball infield drills[/tag] that can work with all age groups.
One [tag]baseball drill[/tag] that I would recommend that is used often times in basketball to help teach proper defense is the feet shuffle on the whistle.
The players line up in two lines and the [tag]baseball coach[/tag] has a whistle. The coach blows the whistle and the team begins to shuffle their feet with their knees bent and head up in the direction that the coach points until the coach blows the whistle again at which time they switch directions. This is continued side to side and forward and backwards.
This [tag]baseball[/tag] drill helps to strengthen the players legs as well as teach shuffling their feet which will help them develop proper fielding techniques.