One coach stands 20' from home plate down the 1st base line another coach stands 20' down the 3rd base line. Each coach will need a catcher. Split the team up with half of the players at the SS position and half at the 2B position. The coach standing down the 1st base line hits ground balls to the players at SS. The coach along the 3rd base line hits to the players at 2B. Balls are fielded and thrown back to the catcher assisting the coach that hit ball. After a few times through the line, have the players switch position. You can also have each player run to the back of the other line after fielding each ball.