Finding the Surface Area of a Cube

Finding the surface area of a cube

In order to introduce the concept of surface area to students in the 5th grade, I will show them use manipulatives to provide visual aids of what a cube is, such as a gift box where all sides of the box are congruent. I will tell them that today we are going to learn how to find the surface area of a cube, such as the gift box. One way to measure a solid is to find the area of its surfaces. We can find how much surface a cube has by adding the area of all of its faces. The sum of these areas is called the surface area.

Some prerequisite skills that the students need in order to solve a problem involving the surface area of the cube, is to know measurements, how to use a ruler, how to find area, and have basic computation skills in addition and multiplication.

In order to remind the students how to find the area, we will practice finding the area of a square. I will make sure that students remember that to find the area of a square, we take the length times the width:

L X W=A

We will practice this by measuring with our rulers the length and width of the square cut out that I give to each student. The length of the square is 5 inches and the width of the square is 5 inches. Once the students measure and give me those numbers, I will prompt them to tell me what we do next (plug the numbers into our formula). Then we will take

5X5=25

The area of our square is 25 square inches.

Students will need to understand how a two dimensional object, such as a piece of paper, into a three-dimensional object, to make a cube. We will make a cube out of a piece of paper, and then count how the faces of the cube, to make sure that the students understand that the cube has six faces. A two dimensional pattern that folds to make a three dimensional shape is called a net. I will have the students use a ruler to duplicate each net on grid paper and then use scissors to cut out each net and fold it along the dashes to learn what shape it forms. Students will be able to better understand what a cube is if they have one that they have made to look at and refer back to. I will explain to the students that a cube is rectangular prism. A rectangular prism has six surfaces. All six faces of a cube are congruent. Therefore, in order to find the surface area of a cube, we simply need to multiply the area of one side by 6.

To calculate surface area, you add the area of the six sides.

First, add the area of two faces -top and bottom.

Next add area of two faces-sides.

Next add area of two faces-front and back.

By doing this we come up with a formula to find surface

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