Metric Area and Volume
It has always been common to measure areas in square units. Square inches of glass, square feet (or board feet) of wood, square yards of carpeting, square miles of ranchland. How many square inches are there in a square yard? (answer below). The square meter was a naturally derived unit as soon as the meter was defined. It is a little larger than a square yard since the meter is a little longer than a yard. A square that is 10 meters on a side has an area of 100 square meters, or one are (pronounced: R). A square that is 100 meters on a side has an area of 10 000 square meters, or one hectare, and a square that is 1 000 meters on a side is a square kilometer. There are 1 000 000 square meters in a square kilometer, just as there are 1 000 000 square millimeters in a square meter. You might think of a square millimeter as the area of a pinhead, and a square meter as the area of a desktop. The 10 meter square or are is about the floor area of a large classroom, and the hundred meter square or hectare is about the area of two football fields. The square kilometer is about 200 acres, or roughly a third of a square mile.
Cubic units were used to measure volumes long before the metric system was defined. Cubic inches of ice (ice cubes), cubic feet of water (purchased from the water company), and cubic yards of dirt, gravel, or concrete (7 to 10 of them per truckload) are still in common use. The cubic meter (stere) is 30% larger than the cubic yard. How many cubic inches in a cubic foot? (answer below) There are exactly a billion cubic millimeters in a cubic meter, and a billion cubic meters in a cubic kilometer. A cubic millimeter is about the volume of a pinhead, and a cubic meter is about the volume of a desk.