Print paper centimeter rulers from the "Vendian Systems" or "TeacherVision websites or "PrintARuler.com" and distribute them to students. Ask students to measure the length of one personal item, such as a pencil or a notebook, both with their regular ruler and the paper centimeter ruler. Instruct students to divide the centimeters value by the inches value and vice versa. The results must be 2.54 and 0.4 respectively. These two numbers show the relation between inches and centimeters.
Use a scale to weigh pounds in the classroom. Instruct students to take turns and measure their body weight. Each student writes down her body weight in a notebook. Write on the board: "1 pound equals to approximately 0.45 kilograms." Instruct students to multiply their body weight by 0.45 to determine the metric value. Instruct students to divide their weight in pounds by their weight in kilograms to find out how many pounds equal 1 kilogram.
When measuring long distances, we use feet or yards, not inches, while in the metric system, kilometers are used for distances longer than 1,000 meters. Draw an aircraft on the board, flying at 20,000 feet, and a quarterback who throws a 50 yard pass. Write on the board: "1 foot is 0.3 meters; a yard is 0.91 meters." Instruct students to determine how high the aircraft flies in meters (which is 6,000 meters or 6 kilometers on this example) and the length of the pass (45.5 meters).
Temperature in the United States is measured in degrees Fahrenheit, while the metric system uses degrees Celsius -- most commonly -- or Kelvin. Divide the board into three sections: in the first section from the left write "Deduct 32" on top and "Add 32" on the bottom. At the second section, write "Multiply by 5" on top and "Divide by 5" on the bottom. In the third section write "Divide by 9" on top and "Multiply by 9" at the bottom. Instruct students to move from left to right and follow the instructions on top to convert Fahrenheit to Celsius. to convert from Celsius to Farenheit, instruct students to move from right to left and follow the instruction. Ask students one at a time, to write their answers on the board.