Fourthgrade students begin to use the formula "base times height" to find the area of shapes. Previously, in third grade, students found the area of rectangles and squares by using centimeter tiles or grid paper. Fourthgrade students build on that concrete knowledge of area and apply the formula to determine the area of a polygon.
Knowledge to Build Upon

Understanding how to find the area of a rectangle is the first introduction to area. Formulas for finding the area of triangles, circles and other twodimensional shapes are explored in later years. In third grade, students counted the number of tiles it takes to cover a shape, or they used grid paper and counted the units. This practice provides a strong foundation in finding area before moving on to the more conceptual method of using the general formula. Practice this step with students by handing out tiles and asking them to make a rectangle with a specified area.
Base x Height

If the base of a square is three tiles (or units) long and three tiles (or units) high, students in third grade covered the square with nine tiles. The area of that square is nine square units. Base and height can also be referred to as length and width. In fourth grade, ask the student to count how many units are on the base of the square and how many units make up the height. The student places those numbers in the formula, base x height, or 3*3, and the answer to that multiplication problem is the area in square units.
Real World

Fourth graders are asked to apply their knowledge of area to real world problems. Finding the area of the classroom or their bedroom are both examples of real world problems. Fourth graders need to know the difference between area and perimeter. Ask groups of students to make a chicken coop with 20 yards of chicken wire and to find the area and perimeter of their chicken coop. Let them map it out on the parking lot. Each group will probably have a unique design. Check their area and perimeter measurements and discuss the differences of each.
Missing Measurements

Fourthgrade students apply their knowledge of area and the formula to find missing factor measurements. If students know the area and the width, they need to find the missing length measurement. Give your students an example to discuss with their group. For example, if a playground has an area of 150 square yards and the width of the playground is 10 yards, what is the length of the playground. Students place what they know in the formula and find the missing factor. In this example, 150 square yards = 10 yards x Length. To find the missing factor, students divide  150/10 = 15. The length of the playground is 15 yards.
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