LESSON: Measuring Units

READ: Choosing Appropriate Units of Measure

Choose Appropriate Metric Units of Measure

When you think about the metric units for measuring mass, how do you know when to measure things in grams, milligrams or kilograms? To really understand when to use each unit of measurement we have to understand a little more about the size of each unit.

Let’s compare grams with ounces. Grams and ounces measure really small things like a raisin.

Let’s compare kilograms with pounds. Kilograms and pounds measure bigger things, like a textbook.

What about milligrams?

Milligrams are very, very tiny. Think about how small a raisin is and we would use grams to measure that. Scientists are people who would measure the mass of very tiny items. These things would be measured in milligrams.

If you think about things that would be seen under a microscope, you would measure the mass of those items in milligrams.

A milligram is of a gram.

What about capacity? How do we choose the correct unit of measure to measure capacity?

There are two metric units for measuring capacity, milliliters and liters.

This comparison may seem a little more obvious that the units for mass. A milliliter would be use to measure very small amounts or ounces of water. A liter would be used to measure much larger volumes of water.

A milliliter is of a liter.

How about measuring length? The metric units of length are millimeter, centimeter, meter and kilometer. When is the best time to use each measurement?

A millimeter is the smallest unit. There are 10 mm in one centimeter, if an object is smaller than one centimeter, then you would use millimeters.

Who would use millimeters? A scientist measuring something under a microscope might use millimeters to represent a tiny specimen.

A centimeter is the next smallest unit. We can use a ruler to measure things in centimeters. If an object is the length of a ruler or smaller, then it makes sense to use centimeters to measure.

Meters are used to measure everything between the length of a ruler and the length of a far distance, like the distance between two cities or places.

Most household objects such as table, rooms, window frames, television screens, etc would be measured in meters.