Tennis coaches everywhere have probably already played this game inadvertently. Who of us hasn't been feeding balls quickly, reaching into the cart automatically, only to have the drill come to a screeching halt - or at least have the students screeching, "Hey! That was an orange (red/green/yellow) ball!" When this happened to me for the umpteenth time the other night, I figured, why not do it on purpose and make it into a fun reaction time exercise?
If you have an opaque hopper such as the Gamma black fabric bag hopper, this will be more fun. If not, try to block the cart/hopper from view as you are feeding. Load the cart with a variety of red, orange, green, yellow, and yes, even foam balls if you have them. Players must play whatever ball is fed, luck of the draw. This should improve reaction time and control.
Use this on stroke-specific lessons such as backhands or forehands.
Use it for a fun feeding drill such as Squirrel Crossing.
Great for lessons on touch such as volleys and drop shots.