Metric Units of Length, Mass, and Capacity

The Metric System The metric system of measurement is a decimal system that uses prefixes to relate the sizes of units to standard units. The standard unit of length is the meter. The standard unit of mass is the gram. The standard unit of capacity is the liter.

Metric Prefixes kilo1,000 hecto100 deka10 deci0.1 centi0.01 milli0.001

Length (distance) The standard unit is a meter. A meter is about the distance from the floor to the doorknob on a door. 1,000 meters make a kilometer. It is roughly 0.6 of a mile long. To run a kilometer, you would have to run around a track two and a half times. A centimeter is smaller than a meter. It takes 100 centimeters to make a meter. The thickness of a CD case is about 1 cm. A millimeter is very small. It takes 1,000 mm to make a meter. The thickness of a CD is about 1 mm.

Measuring Metric rulers show centimeters and millimeters. Line up the zero (or edge of the ruler if there is no zero) with the edge of what you’re measuring. The line is 5.3 cm long. You could also read it as 53 mm.

Mass – the amount of matter that an object has. The standard unit is a gram. A gram is about the mass (or, basically, the weight) of a paper clip. 1,000 grams make a kilogram. You would use kilograms to measure heavier things, like desks and people. A kilogram is roughly equivalent to the weight of a one liter bottle of water. A newborn baby weighs about 3 kg. A milligram is very small. It takes 1,000 mg to make a gram. An eyelash weighs about 1 mg.

Capacity – the amount of liquid an object holds. The standard unit is a liter. A bottle of juice holds about a liter of liquid. 1,000 liters make a kiloliter. If you filled 2-3 bathtubs with water, you would have about a kL of water. A milliliter is very small. It takes 1,000 mL to make a liter. A couple of drops of water would be equivalent to 1 mL. You would use milliliters to measure how much liquid was in a glass, or a juice box, or a can of soda.

Making Conversions You can convert from one metric unit to another by multiplying or dividing by a power of 10 (10, 100, 1,000, etc). When changing from larger units to smaller units, you multiply. When changing from smaller units to larger units, you divide.

Example 4.2 m = ______ cm Meters are larger than centimeters Converting from large units to smaller units requires multiplication. Multiply 4.2 by 100, since there are 100 centimeters in a meter. To multiply by 100, move the decimal point two spaces to the right. 420

Example 2 36 g = ______kg We are going from a smaller unit to a larger unit, so we divide. Divide by 1,000 since there are 1,000 grams in a kilogram. To divide by 1,000, move the decimal point three spaces to the left..036