I remember trying to jump our 'Swimming pool' on mine, empty, in ground, concrete, rectangle that was all of 10x5ft wide and 3ft deep. We practiced safety though, I had long pants on and wore a crash baseball cap! I remember my sister and a couple of local kids standing next to our 'concrete pond!' as I hit the ramp of cardboard. Next thing I remember is being on the bottom of the pool with a flower laying on me and all the other kids gone. My ever thoughtful sister thought I was dead so placed the flower on me and went to watch TV Apparently the afternoon cartoons were starting! They were more important than telling my mother I was laying unconscious at the bottom of the pool. A couple of weeks later I finally made it across on the Bigwheel. We threw lawn clippings in there so if I didn't make it again I had a soft landing. You know what? This may explain a lot............... Doc.