FYI: there are no good short videos about yeast on youtube or good books about yeast at our library. If you know of any good resources, please shout them out. We liked these videos the best: http://www.youtube.com/watch?v=w-GmnAD4J7E and http://www.youtube.com/watch?v=gYXjURcBk98. We also really liked this one on how to make a sourdough starter: http://www.youtube.com/watch?v=pmLmpJhumSM, although we didn't make ours like he did. We used grapes.
I was nervous about doubling the recipe as I had never used sourdough before, hence the two bowls. Sourdough is a lot more forgiving than I thought.
Another sidenote. I have now made sourdough waffles and used the leftover batter the next morning for sourdough pancakes. This adventure into the land of sourdough has taught me that I prefer my regular waffles as the texture of sourdough waffles is a little rubbery. I liked the pancakes more. I also learned that sourdough is alive and continues to grow so put leftover batter in a big enough container to control the growth. Otherwise, you wind up cleaning out your fridge.