Help with 4th Grade Math: Finding the Area of Shapes

Area of Shapes for 4th Graders

What Is Area?

In 3rd grade, you probably learned that the area of a shape is its surface. You can divide the area up into smaller sections; for example, you can divide the area of a square into four smaller squares, each of which represents 1/4 of the square's total area. Likewise, you could divide a rectangle into two, four or eight sections. These would be equal to 1/2, 1/4 and 1/8 of the rectangle's area, respectively.

Discovering the Area Formula

If you're in 4th grade, you probably already understand the concept of multiplication and can fluently multiply with single-digit numbers. This means you already have the skills necessary to find the areas of simple shapes, like squares and rectangles. Here's an activity that will help you understand how to calculate area. You'll need the following items:

• A ruler
• A pencil
• A piece of paper

Here are the instructions:

1 Use your ruler to draw a rectangle that's five inches tall and three inches wide. Then, draw another rectangle that's three inches tall and five inches wide. When you draw each rectangle, mark the inches (one, two, three and so on) along all four sides.

2. Now, use these marks to divide each of the rectangles into smaller squares. For instance, you'll draw three horizontal lines across the rectangle that's three inches tall, one line at each inch mark. Then, you'll draw five vertical lines since it's five inches wide.

3. Each of the blocks you've drawn should be one inch tall and one inch wide. These are called square inches, and they are the units you'll use to report the areas of your rectangles.

4. For each of the two rectangles, measure the height and width in square inches, and then multiply them together. For example, one of the rectangles should be three blocks tall and five blocks wide, so you'd multiply three by five.

5. The answer you get when you multiply the height and the width together is the area. For instance, if the height is three square inches and the width is five square inches, then the area is 15 square inches (3 x 5 = 15).

6. To check your answers, count the number of sections you've drawn in each rectangle. This number should be the same as the one that you got from multiplying (15).

7. Notice that even though the rectangles are different shapes (one is tall and narrow, the other is short and wide), they have the same area.

8. Turn your piece of paper over and experiment with some squares and rectangles of different sizes. Remember that the total number of square inches you divide the shape into gives you its area.