Open your sugar cube box on a clean, flat surface. Separate those that are stuck together, and organize the rest of your work space. Make sure you are far from any moisture, as even condensation from a cup of water could cause a sugar cube meltdown and ruin your pyramid.
Place a small dot of glue on one side of a sugar cube, and stick it glue side down onto the cardboard. Repeat this process to make a square of 10 cubes across on all four sides. Allow to dry, and make sure this outer level of your pyramid is placed where you would like it to be.
Make a second layer of glued cubes, this time using nine in each row. Indent this second row so it is a few centimeters away from the first row's border. Repeat this process, reducing the amount of sugar cubes in each row, each time. For example, your third row will contain four sides of eight, your fourth row will have seven, etc., until you reach one cube.
Allow all of the glue to dry, and add extra glue on any loose cubes. When your pyramid is dry, paint it any color you'd like. Gold or tan spray paint is popular, as is yellow and brown. If you haven't been given any specific rules, ask your teacher if you can do some sort of wild pyramid with bright colors and decor for fun.
Glue any paper palm trees, outer sand or gravel, or anything else you'd like to your cardboard to add to the overall ambiance of your pyramid. Carefully transport your pyramid to school, using a baking sheet or another solid surface to support the cardboard's weight.