That feeling

Have you ever had that feeling when taking a test? You do fine on the first page, turn to the next, and have no idea how to do any of it? Happened to me in chem. I tore through the first page but when I turned to the second I had no idea how to do any of it. All of the questions used one formula and I didn't remember it. Worst part is that the first page was 10 points and the second page was 30 points. Oh well, 6 more weeks of this teacher. Time to hit the books.