"a long dowel
a cardboard tube or a two liter bottle or a can
8 index cards
You may use scissors in construction but not the solution. "
I'm not an engineering person by any stretch of the imagination, so we googled some images of water wheels, and this is what Billy came up with:
It worked great for a couple of seconds until the cards got too wet. I was just using thick paper rather than cardboard though.
We didn't end up using the string - I guess that was for the 2nd half of the challenge to connect it to the boat. We probably could have also used it to suspend the dowel in the middle of the tube, but we were satisfied with what we did for the first time at the challenge.
We also didn't use the sharpie. Other than for Billy to draw up his blueprint in the first place :)