Folding a Fitted Sheet How-To from Martha Stewart
1. Start with your sheet inside out. While standing, hold the sheet in front of you, and place one hand in each of two adjacent corners.
2. Bring your right hand to your left, and fold the corner in your right hand over the one in your left hand, so that the corner on top is right-side out.
3. Keeping your left hand in place, reach down to the remaining two corners with your free hand, and tuck these corners into each other. Fold these corners over the first two. Your sheet should now be folded in quarters, with all four corners tucked inside one another.
4. Lay the sheet on a flat surface with the puckered end folded in over the flat part of the sheet. Touch up with an iron, if necessary, at this point. Fold two edges in, so all the elastic is hidden.
5. Fold the strip you have created into a rectangle, then continue folding until the rectangle is the size you want it to be.