First, students can be shown a square along with the length of its sides. Ask students to calculate its area. Next, pass out several cubes to the class so that there are enough for everyone to look at. These cubes should preferably have the same approximate side measurements as the square previously displayed. After explaining that surface area is the total area of the surface on the outside of an object, ask students how many sides there are, and what the shape of each side is. Ask them to make the connection themselves as to how to find the surface area of the cube. If they do not get it at first, hold up a picture of the square they just found the area of and compare it to the sides of the cube. They should be able to recognize that to find the surface area of the cube you multiply the area of the square by the number of squares/sides on the cube.
Another good introduction or way to reiterate an understanding of how to find the surface area of a cube is to transform a two-dimensional drawing into a three-dimensional object. Pass out pieces of paper with six large squares on them. These squares should be arranged in a way that four are next to each vertically and one square is on each horizontal side of the third square. (It should resemble a cross).