How do you explain it a ball is hollow in the middle?

A ball is hollow in the middle because it is designed with an outer shell that encloses an empty space. This construction reduces the weight of the ball while maintaining its shape and structural integrity. The hollow design can also enhance performance, such as improving bounce or allowing for air to be trapped inside, which can affect how the ball moves through the air. Essentially, the hollow center contributes to the ball's functionality and usability in various sports.