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Here you will learn about metric units of measurement. You will look at common units of measurement in the metric system of measurement and learn about their relative sizes.

Students will first learn about metric units of measurement as part of measurement and data in 4 th grade.

**Metric units of measurement** are the international system of units (SI units) and include the standard units of length (meter), mass (gram), capacity (liter) and time (second).

The **metric system** is based on powers of 10 (the decimal system). The metric prefixes along with the basic unit vocabulary help identify their standard unit and size.

The prefix “**milli**” means \cfrac{1}{1000} \, th.

For example,

A **milli**meter is \cfrac{1}{1000} \, th of a meter.

A **milli**liter is \cfrac{1}{1000} \, th of a liter.

The prefix “**centi**” means \cfrac{1}{100} \, th.

For example,

A **centi**meter is \cfrac{1}{100} \, th of a meter.

A **centi**liter is \cfrac{1}{100} \, th of a liter.

The prefix “**deci**,” “**deca**,” or “**deka**” means \cfrac{1}{10} \, th.

For example,

A **deci**meter is \cfrac{1}{10} \, th of a meter.

A **deci**gram is \cfrac{1}{10} \, th of a gram.

The prefix “**kilo**” means 1,000 times larger.

For example,

A **kilo**meter is 1,000 times larger than a meter.

A **kilo**gram is 1,000 times larger than a gram.

Since there are many different units for measuring, it is helpful to think about each unit in relation to something in the real world. Let’s look at some common units and their relative sizes.

One way to measure an object is length – the distance from one point to another. In the metric system, a meter is the base unit for length.

One way to measure an object is mass – the weight of an object. In the metric system, a gram is the base unit for mass.

Note: A tonne is also referred to as a metric ton, but is NOT the same as a customary ton (2,000 pounds ).

One way to measure an object is capacity – how much space something takes up. In the metric system, a liter is the base unit for capacity (also referred to as the base unit of volume).

One way to measure an event is time – the length of an event with a clear starting and ending moment. In the metric system, a second is the base unit for time.

Note: All of these time measurements are very small, and it can be harder to tell the difference between them on our own.

How does this relate to 4 th grade math?

**Grade 4 – Measurement and Data (4.MD.A.1)**

Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table.

For example, know that 1{~ft} is 12 times as long as 1 {~in}. Express the length of a 4{~ft} snake as 48{~in}. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), …

In order to choose a metric unit of measurement:

**Decide if the measurement is length, mass, capacity or time.****Consider the size.****Write down the most reasonable choice.**

Use this quiz to check your grade 4 to 5 students’ understanding of units of measurement. 10+ questions with answers covering a range of 4th and 5th grade units of measurement topics to identify areas of strength and support!

DOWNLOAD FREEUse this quiz to check your grade 4 to 5 students’ understanding of units of measurement. 10+ questions with answers covering a range of 4th and 5th grade units of measurement topics to identify areas of strength and support!

DOWNLOAD FREEWhat are the most appropriate units to measure the width of a hand-held calculator?

**Decide if the measurement is length, mass, capacity or time.**

Width is a measurement of length, so you need to consider the measurement units based on the meter (m).

2**Consider the size.**

Thinking about the size of a hand-held calculator, a meter (about the length of a baseball bat) is too large, or a unit and millimeters (about the width of the tip of a pencil) are too small.

3**Write down the most reasonable choice.**

Centimeters (each about the width of a fingernail) is the most appropriate unit to measure the width of a hand-held calculator.

What are the most appropriate units to measure the distance between London and Paris?

**Decide if the measurement is length, mass, capacity or time.**

Distance is a measurement of length, so you need to consider the measurement units based on the meter (m).

**Consider the size.**

A meter is about the length from the tips of your fingers when you spread your arms out wide.

The distance from these two cities, which are not in the same country, is much greater than a meter (m).

**Write down the most reasonable choice.**

Kilometers (km) is the most appropriate unit to measure the distance between London and Paris.

What are the most appropriate units to measure the weight of a large dog?

**Decide if the measurement is length, mass, capacity or time.**

Weight is a measurement of mass, so you need to consider the measurement units based on the gram (g).

**Consider the size.**

A tonne (about the weight of a small car) is too big. A gram (about the weight of a penny) is too small.

**Write down the most reasonable choice.**

A kilogram (each about the weight of a pineapple) is the most appropriate unit of measurement for the weight of a large dog.

What are the most appropriate units to measure the weight of a pencil?

**Decide if the measurement is length, mass, capacity or time.**

**Consider the size.**

A kilogram (about the weight of a cantaloupe) is too big.

**Write down the most reasonable choice.**

A gram (each about the weight of a paper clip) is the most appropriate unit of measurement for the mass of a pencil.

What are the most appropriate units to measure the amount of tea in a tea cup?

**Decide if the measurement is length, mass, capacity or time.**

The amount of tea is a measurement of capacity, so you need to consider the measurement units based on the liter (l).

**Consider the size.**

A liter (about the amount in a quart of milk) is too large.

**Write down the most reasonable choice.**

Milliliters (each about 1 drop of water) is the most appropriate unit of measurement for the capacity of a tea cup.

What are the most appropriate units to measure the amount of water in a pond?

**Decide if the measurement is length, mass, capacity or time.**

The amount of water is a measurement of capacity, so you need to consider the measurement units based on the liter (l).

**Consider the size.**

A milliliter (about 1 drop of water) is too small.

**Write down the most reasonable choice.**

Liters (each about the amount of 4 cans of soda) is the most appropriate unit of measurement for the capacity of a pond.

- Worksheets can be helpful for this skill, but not before students have real life experiences with the different metric units. It is much easier to understand metric units if their use is connected to a memory or experience.

- Putting up a “units of the metric system” poster in the classroom can be helpful for students to reference as they are learning the different types of measurements. Particularly if they are used to using the customary system and have less exposure to the metric system.

- This skill should be taught before metric conversions (unit conversions). Once students have experience using metric units and understand their relative size, they are ready to start converting units.

**Confusing metric and customary units**

A common error is to confuse metric units with customary units of measurement. There are conversion rates between them, but they are different units in different systems.

For example,

1{~inch} ≈ 2.5{~cm}

1{~foot} ≈ 30{~cm}

1{~mile} ≈ 1.5{~km}

**Thinking the amount of substance changes when a measurement is converted**

When a measurement is converted to another unit, the number representing it becomes smaller or larger. This is not because the amount being measured changed, but the way it was being measured changed.

For example,

\$1 = 20 nickels

Converting \$1 to 20 nickels, increases the 1 to a 20, but since nickels are a smaller unit the overall value of \$1 has not changed. The conversion just shows that it takes 20 nickels to equal \$1.

**Thinking the millionth is the smallest unit in the metric system**

While this unit is very, very small, there are other units even smaller. Because the conversion factors in the metric system are based on the decimal system, and the decimal system goes on forever (decreasing by powers of 10 infinitely), in theory there is no end to the units that can be measured in the metric system.

The metrics units that currently exist are based off the tools we have available to measure – smaller and smaller units often need more sophisticated measuring tools.

**Forgetting about less common units**

There are units that are commonly used in daily life, like liter and milliliter. But there are also units that exist between (or above and below) these commonly used units. They are easy to forget since they are not used often.

For example,

Between liter and milliliter are units between deciliter and centiliter.

Deciliters are 10 times smaller than liters. And centiliters are 10 times smaller than deciliters.

1) Choose the most reasonable metric unit to measure:

The height of a building

meters

kilograms

inches

millimeters

You need a unit for length – so kilograms can be ruled out.

You need a metric unit – so inches can be ruled out.

A building is large, and a millimeter is about the thickness of 10 sheets of paper, so it is too small.

A meter is about the length of a guitar. Meters is the most reasonable unit to measure the height of a building.

2) Choose the most reasonable metric unit to measure:

The weight of a can of beans

kilograms

ounces

milliliters

grams

You need a unit for mass – so milliliters can be ruled out.

You need a metric unit – so ounces can be ruled out.

A kilogram is about the weight of 3 chapter books, so it is too large.

A gram is about the weight of a penny. Grams is the most reasonable unit to measure the weight of a can of beans.

3) Choose the most reasonable metric unit to measure:

The thickness of a chapter book

meters

millimeters

yards

milliliters

You need a unit for length – so milliliters can be ruled out.

You need a metric unit – so yards can be ruled out.

A meter is about the length of a yard stick, so it is too large.

A millimeter is about the thickness of an ID card. Millimeters is the most reasonable unit to measure the thickness of a chapter book.

4) Choose the most reasonable metric unit to measure:

The volume of a medicine dropper

kilograms

pints

milliliters

liters

You need a unit for capacity (volume) – so kilograms can be ruled out.

You need a metric unit – so pints can be ruled out.

A liter is about the amount in a large soda bottle, so it is too large.

A milliliter is about the amount in a drop of water. Millimeters is the most reasonable unit to measure the volume of a medicine dropper.

5) Choose the most reasonable metric unit to measure:

The weight of a sheep

grams

kilograms

pounds

centimeters

You need a unit for mass – so centimeters can be ruled out.

You need a metric unit – so pounds can be ruled out.

A gram is about the weight of a feather, so that is too small.

A kilogram is about the weight of a bunch of bananas. Kilograms is the most reasonable unit to measure the weight of a sheep.

6) Choose the most reasonable metric unit to measure:

The volume of a lake

kilometers

liters

milliliters

gallons

You need a unit for capacity – so kilometers can be ruled out.

You need a metric unit – so gallons can be ruled out.

A milliliter is about the amount in a drop of water.

A liter is about the amount of shampoo in a full bottle. Liter is the most reasonable unit to measure the volume of a lake.

Yes, there are defined conversions that allow you to move between the two.

Besides the units mentioned on this page, there are additional basic units in the International System of Units. Electric currents are measured by amperes. Thermodynamic temperature is measured in kelvin. Luminous intensity is measured in candela. And moles are used to measure the amount of substance.

- Represent and interpret data
- Ratio
- Proportion

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