Start with your 8.5" x 11" sheet of paper on a large, flat surface.
Fold one corner up to the opposite edge so that the edges are flush. Unfold and repeat with the corner that now has a fold through it. Unfold again.
Turn the paper upside down and fold the bottom two corners up to the top two fold marks. All three folds should intersect at one point.
Turn the paper over. Press at the folds' intersection to "pop" the paper out along the first two folds. With both hands, draw the ends of the third fold together and collapse them into a triangle.
Orient the paper so that it looks like a house with a roof. Take one of the corner flaps and fold it up to the peak of the roof. Repeat for the other side.
Unfold the last fold slightly and slip your finger inside, then press down so that the triangle collapses into a square. Repeat for the opposite side.
Grab a corner flap on one of the small squares and fold it up and outward to the adjacent corner. Repeat for the other side.
Take the sides of the "house" and fold them in so that the sides create a 90 degree angle with the bottom. They should tightly "hug" the existing folds near the "roof."
Take the bottom corner and fold it up to the "windows" of the "house," making a triangle. Repeat with the other corner.
Fold the little flap in the middle up to make a triangle.
Fold the peak at the bottom up and tuck it under the little triangle in the middle. Make sure it's pushed tightly against the other folds, and then make the crease along the bottom.
Finish by folding the "roof" down and tucking the peak under the same flap that the bottom is tucked under. Voila!