The other night I was frantically trying to finish dinner as N (6 months) started getting fussy. To distract her, I rolled a small ball onto her highchair tray. Not only did it distract her and calm her down, but as I was watching her I realized that it is a simple activity to help develop visual tracking skills and coordination.
When she bats at it, it rolls around the outside of the tray. As she follows it, she is improving her visual tracking skills. As it rolls around and down toward her and she tries to grab it she is strengthening her coordination.
Oh and when she does finally grab it and then throws it on the floor (over and over again) I have to remind myself that she is experimenting with cause and effect. =)