I have tried this a few times and have looked through the manual but I can't seem to get it to work right. I inserted a particle emitter, rotated it 180 degress and stuck it on the ceiling. I then placed a sphere midway between the emitter and the floor. When I scrub the slider I want the particles to bounce off (deflect) off the ball and then hit the floor. But, right now they just pass throught the ball on their way to the floor. Can someone guide me here? I looked in the Porperties panel with the sphere selected but can't seem to find anything. Thanks, Chris