OK, so this one was all my son's idea. He was busy gathering up items, asking me for this and that. I was busy cleaning up the kitchen from dinner and not really paying too much attention to what he was doing. He went to the cabinet and got a plastic bottle and put a pipe cleaner around the top of it. Then, he set up two of our dining chairs and "tied" a ribbon between them. He was busy making an "obstacle course" he then stated to me. After a few tries, he began to get frustrated that his bottle wasn't going down. It then became clear that he was trying to make a zip line for his plastic bottle to travel on. Dad to the rescue! He found some florist wire in my craft cabinet and tied it to the cabinet and the bottom of the kids play horse. Dad then helped bend the pipe cleaners into a hook so they could easily slide down the wire. The rest was the kids. T set up a box and another bottle to be knocked over by the flying bottle. I am not even kidding when I say they played with this all evening and protested strongly when it was time for bed. I promised that it would stay up as long as they wanted it too. Excellent science activity for a lesson in gravity and inertia.