UPDATE 9/14/2011: TH_NK has updated Pottermore so that you no longer earn house points when you fail to brew a potion, this simple fix nullifies the cheating method mentioned below, Hurrah!
I’m going to preface what I’m going to say below with the statement that I am not putting this post up as an invitation to cheat on pottermore. I would have sent this message privately to the Pottermore developers, however I could find no place on pottermore.com, insider.pottermore.com, @pottermore or pottermore on facebook where I could send a message to the devs. The closest I could find was the Beta Feedback button, which presents a feedback form that lets you rank a page on a scale of how much you like it, but it has no comment field, no way to introduce a comment for the devs.
My hope is that by posting this publicly on my blog, the Pottermore devs will find this post and fix the issue (and perhaps add a method of commenting privately to the devs).