IGD Area of a Rectangle

• ## IGD: Area of a Rectangle

Grade: 3rd to 5th, 6th to 8th

How Do You Find the Area of a Rectangle?

To measure the length of a segment, you use a unit length such as an inch, a centimeter, or a foot, and you see how many times it goes into the segment you are measuring. To measure an area, you use a square unit, such as a square inch, a square centimeter, or a square foot, and see how many times it goes into the area you are measuring.

### Instructions

• Drag point B or D to change the dimensions of the rectangle.
• Point A will not move, and point C will adjust automatically as the dimensions of the rectangle change.

### Exploration

A square unit is the basic unit of measurement of area. To measure an area, find out how many of these go into it.

The unit square fits into the rectangle shown here 15 times, so its area is 15. How can you find the area of any rectangle? In the applet below, the dimensions and area of a rectangle are given. How do you use the dimensions to find the area?

Area of a Rectangle = Base × Height

Use what you know about the area of a rectangle to find the Area of a Parallelogram.

### Objectives and Standards

NCTM Standards and Expectations
• Geometry / Measurement
• Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.
• 3-5
• 6-8
• Geometry