Finding the Surface Area of a Cube - Essay Example

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). After providing the measurements of the sides of the squares, have students calculate the area of each square, and add them together (or simply multiply the area of one square by a number of squares on the page).

Have students cut out the picture, and fold on the lines so that a cube is formed. The tape can be provided to hold them together. The square in the middle that has squares on all sides of it can be the base of the cube. Fold the squares on the sides of the middle square upwards. One of the sides will now have a wall two squares high - fold the top square toward the middle to close the cube. Now ask students again what the surface area of the cube is and have them explain why it is that way, in order to reiterate the concept.

(The following figure shows the two-dimensional picture that can be folded into a cube).Because the sides of a cube are all equal, to find it's a surface area students must find the area of one of its square sides and multiply it by the number of square sides on the cube (which is always six). Having now illustrated this process quite clearly, students should now be asked to calculate the surface area of cubes without seeing them. In other words, provide the dimensions of a cube without providing any sort of diagram and ask them to find the surface area for the given dimensions.

After understanding how to find the surface area of cubes, students will be ready to learn how to find the surface area of more complex objects, such as pyramids, rectangular prisms, and triangular prisms.