You run out of brown sugar and decide to use 1.5 cups granulated sugar instead. The cookies come out much thinner than usual. Formulate a one-sentence hypothesis for why the recipe failed.

Answer 1

The brown sugar contained a substance that made the cookies have more bulk.

Answer 2

I.e. a testable hypothesis, not necessarily accurate, describing why white sugar may not be an effective substitute for brown sugar. Example full credit answer: "Cookies made without brown sugar fail to rise because the brown sugar contributes acid, which reacts with the baking soda to produce gas for leavening."