With respect to the Golden Ratio, check out Andrew Miller's week 11 page and my response thereto.
I agree that writing arguments out in paragraph form soon becomes tiresome, enough to make one appreciate the economy of using symbolic notation. In an interactive version of B3D, I suppose both forms could be made available at the reader's c hoice, and we would know the level of tolerance of each person as we monitored the used of the file. (Someone asked me today if I kept track of the way each student responded to the electronic documents. I answered that I didn't try to do that. I suspe ct that it would distract me.)
On the other hand, there is nothing wrong with getting out that old pencil and paper and trying to figure something out, as for example in the exercise that Dave Stankecarried out. It would be hard to do that just on paper, even with an applet to help.
I also agree that it is nice to see Pascal's figures showing up again. We will have to return to that since we never gave Jeremy a chance to show the model he made more than a month ago generalizing Pascal's triangle to higher space.