How to Make Gingerbread Houses Using Graham Crackers
If you want to make gingerbread houses out of graham crackers, separate 6 graham crackers. Leave 4 whole, but cut 2 with a serrated knife to make angled gables to mount the sloped roof on. Then, use royal icing to hold the sides and roof together, and to paste on any decorations you want. To make royal icing, beat egg whites, lemon juice, and powdered sugar until it is the consistency of peanut butter.
Separate your Christmas candies into bowls. This step saves the hassle of opening bags of candy with sticky fingers later. Place an aluminum pie tin upside down in front of you.  Combine the egg whites and lemon juice in a large bowl to make royal icing. Beat the egg whites on a high speed until they are white and frothy. Add powdered sugar 2 tablespoons at a time to combine gradually, on a speed just high enough that the sugar doesn't fly up all over the counter. The icing should have the consistency of stiff peanut butter by the time all the sugar has been combined. The icing will secure the graham cracker walls of the house and stick the candy decorations to the surface. Place large spoonfuls of the royal icing into quart-size zipped style freezer bags. Avoid regular thickness sandwich bags because the plastic is too thin and will not hold up to the punishment of being used as a pastry tube. An unzipped plastic bag the size of a bread bag will also work, and it will hold more icing. Approximately 1 cup of icing each small bag is enough. If decorating with friends or family, make sure that each gingerbread artist has his or her own bag of icing. Seal the bags.  Use scissors to snip 1/4" (6 mm) off one corner of the icing filled bag. You now have an "icing tube". As you decorate, you'll squeeze the icing toward the snipped corner and use it to dispense a bead of icing on your gingerbread house. Count out six whole, uncracked, unseparated, unbroken crackers. Set four of them aside to form the roof and the two long sides of your house. Cut the two remaining cracker sheets to form end gable pieces. Use a gentle "sawing" motion with a serrated knife. Use the short end of a cracker to measure the angled line from the center of the long side to the centerline of the cracker. Repeat for the second gable end.  Squeeze icing along the edges of a gable end and 1 whole graham cracker.  Place the long edge of the wall cracker vertical to the base edge of the gable end cracker. Stick the side edge of the gable end cracker to the bead of icing on the flat side of the wall cracker. The walls should hold each other up. Add the other gable end and wall in the same manner. Use a bead of icing along the bottom to stick the pieces to the pie tin. Also, use a bead of icing where the two walls will join at the corners. Add the roof crackers in the same manner as the wall crackers, but pipe the icing on the flat of the roof, not on the edges. Then, stick the flat of the roof to the top edges of the gable ends and walls. Allow the icing to set for 15 to 20 minutes before handling the house again. If you place candies on it too quickly, you risk collapsing the house. Line the roof with icing where you want to add shingles.  Add the shingles using your chosen candies. You can also use cereal for the shingles. Use your imagination and decorate the entire house whatever way you like.  
Separate your Christmas candies into bowls. Place an aluminum pie tin upside down in front of you. Combine the egg whites and lemon juice in a large bowl to make royal icing. Place large spoonfuls of the royal icing into quart-size zipped style freezer bags. Seal the bags. Use scissors to snip 1/4" (6 mm) off one corner of the icing filled bag. Count out six whole, uncracked, unseparated, unbroken crackers. Cut the two remaining cracker sheets to form end gable pieces. Repeat for the second gable end. Squeeze icing along the edges of a gable end and 1 whole graham cracker. Place the long edge of the wall cracker vertical to the base edge of the gable end cracker. Add the other gable end and wall in the same manner. Add the roof crackers in the same manner as the wall crackers, but pipe the icing on the flat of the roof, not on the edges. Line the roof with icing where you want to add shingles. Add the shingles using your chosen candies. Use your imagination and decorate the entire house whatever way you like. 