What are Square Centimeters?
A square centimeter is the area of a square 1 centimeter on each side, which is 100 square millimeters or 0.0001 square meters. A postage stamp is a few square centimeters.
What are Acres?
An acre is 43,560 square feet, which is about 4,047 square meters. It was originally the amount of land a yoke of oxen could plough in one day.
The United States and United Kingdom still measure land in acres, but most of the world uses hectares, which fit neatly into the metric system. One hectare is about 2.47 acres.