SIZING UP EARTH - A UNIVERSAL METHOD FOR APPLYING ERATOSTHENES EARTH MEASUREMENT

This article is based on an activity used in a team-taught preservice course, ''integrating Geography and History,'' at the University of No rth Alabama. The antecedents to modem descriptions and calculations of earth's shape and size began more than 2,000 years ago. The Greek mat hematician and geographer Eratosthenes made the most accurate ancient measurement of Earth based on fundamental math concepts and Earth-Sun relations that provided a basis for determining latitude with greater accuracy. A brief historical statement about Eratosthenes' experiment is followed by an extended explanation of how teachers can use Eratost henes' method in the classroom to calculate the size of Earth using sh adows and simple mathematics independent of noon time observations.