I have made the same observation so I keep the sheets wrapped in plastic and I usually place a few old dried out sheets on the top and bottom of the stack for added insulation. Kathryn H. Thompson, PhD, RD Associate Professor and Chair Department of Biochemistry and Nutrition College of Osteopathic Medicine 11 Hills Beach Road Biddeford, ME 04005 voice: 207-602-2216 fax: 207-602-5931 e-mail: [log in to unmask] >>> Staci Johnson <[log in to unmask]> 04/12/08 10:36 AM >>> I have also had some problems with the IF-AT sheets, but discovered something that has been helpful. Most of my sheets have been taken out of the plastic and stored in a manila envelope. The sheet that has been on top is almost always impossible for scratch off. When I pull the sheets from the middle of the stack, they scratch off with little to no problems. I think that as the sheets age, they dry out and then the problems with scratching off to reveal answers occurs. I am more careful to keep the sheets stored in their plastic wrap where they are less likely to dry out. Staci Johnson Southern Wesleyan University