The U.S. Federal Government has decided that it will switch to a metric-based system of weights and measures. Because the government purchases concrete for many of its construction projects, this switch will certainly impact the concrete industry. One of the most significant effects will be the switch to metric units by the Federal Highway Administration. The United States will be using units belonging to the International System of Units (SI). This is one of several metric systems currently in use in the world. The SI system, as adopted by the United States, is composed of nine base and supplementary units, a large number of derived units, the prefixes that are used with the base units and derived units to indicate powers of ten, and several other units not actually part of SI. Here are several key pointers from contractors who have recently gone through the transition to metric units: * At first, don't try to learn more than you need to do your job. You can learn more later. * Don't attempt to function in a dual-unit environment. Use of dual units prolongs the learning experience. * Try to develop a feel for SI units by using benchmarks that have meaning in you day-to-day activities.