[psquared89]

You can do either one, that depends on what's happening in your animation. If the ball is moving, then moving it off the screen is just fine. If it's not, then you'll have to make it disappear. Besides that, once things have moved off of the current camera view (and aren't going to return), it's usually a good idea to make them disappear anyway, so that they don't suddenly reappear if you move your camera.

As for making it disappear, you can either:

Animate the visability (as posted by rowe above) or animate the opacity of the material that's applied to it. Either way, you can use a combination of AutoKey and the Curve Editor to achieve success. As some else mentioned above, tutorials are your friend, in this case, the bouncing ball is a good choice to learn the curve editor.

Also, I'm assuming that you're a part of Team 65 the Huskie Brigade, which is Pontiac Nothern if I'm correct. Watch for emails and information from Randy Rockafeller and SEAM FX, which is a local, Detroit based group of professional animators who give workshops to FIRST teams, usually for free. I know Randy mentors a team, though I can't remember which one. I remember their animation involved a jungle trek, leading to a volanco with robot parts in it, that blew up and the parts fell together into a robot, or something like that, maybe someone else on CD knows which team that was and can help you out. SEAM FX is a great resource, they hold monthly meetings, and, for us anyway, they're local.