Zipline

 I wanted to make a zipline in my backyard. First I tried with rope but it was too saggy and you just hit the ground, so we bought some wire. That was better, but then the pully I was using wouldn't work because thewire was too slippery so the wheel coudn't turn. So Dad and I made a wooden box with ball bearings that wenton the wire and that worked. Well, the first version broke when mum went down he zipline so we had to make another one with stronger wood. It was really satisfying when it finally worked because of how long it took tosolve all the problems.