Epic Fail

So, for one of my baking classes, we had to choose a recipe and change one ingredient 2 times to show how it changes the recipe.  We chose chocolate chip cookies and chose to change the flour used in the cookies.  The original recipe calls for pastry flour. I've made these cookies before at school with pastry flour and they turned out awesome.  Well this time, I used all purpose flour.  Not just any all purpose flour, Meijer brand all purpose flour.  This was the result.  The cookies burned on the bottom and were completely soupy in the middle.  I had to use a spoon to get the cookies off the cookie sheet!  I asked one of my Chefs why this would have happened.  I've made plenty of chocolate chip cookies with all purpose flour and they NEVER turned out this horribly.  I found out this, that all flour is different from batch to batch, from brand to brand.  For the most consistent flour, you should stick to a name brand flour, such as Pillsbury or King Arthur (although I can never find King Arthur anywhere).   Sometimes buying the store brand isn't the best I guess.