Metric System

Metric System

Middle School

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Learning Objectives

• Define the metric system and its base units for length, mass, volume, and time.

• Explain the difference between the concepts of mass and weight.

• Identify the standard metric prefixes and their corresponding values.

• Apply the metric staircase method to convert between different metric units.

Key Vocabulary

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Mass

The amount of matter an object contains, which never changes with its location.

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Weight

A measure of the force of gravity on an object, which can change.

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Volume

The total amount of three-dimensional space an object or substance occupies.

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Metric System

A decimal-based measurement system used globally for scientific and standard purposes.

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Meniscus

The curve seen at the top of a liquid held in a container.

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Measurement Systems: Metric vs. Imperial

Metric System

• ​This is a decimal-based system, meaning it is based on units of ten.

• ​​It is also called the International System of Units, or SI for short.

• ​Developed in France, it is the standard system used by most of the world.

Imperial System

• ​This system originated in the British Empire and is also called the British Imperial System.

• ​​Today, it is officially used in only three countries: the United States, Liberia, and Myanmar.

• ​Common units in this system include feet, inches, pounds, and ounces for measurement.

Multiple Choice

Which statement accurately describes the key difference between the Metric and Imperial systems?

• The Imperial System is a decimal-based system used worldwide.

• The Metric System uses units like feet, pounds, and ounces.

• The Imperial System is also known as the Système Internationale (SI).

• The Metric System is a Base 10 system used by most of the world.

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Basic Metric Measurements

Mass

• Mass is the total amount of matter that is contained within an object.

• The base unit for measuring mass in the metric system is the kilogram (kg).

• It is measured using a Triple Beam Balance or an Electronic Balance.

Volume

• Volume is the total amount of three-dimensional space an object or substance occupies.

• The base unit for measuring volume in the metric system is the liter (L).

• It is measured with a graduated cylinder for liquids or a metric ruler.

Multiple Choice

What are the correct base units for mass and volume in the metric system?

• Newton (N), and Liter (L)

• Gram (g), and Milliliter (mL)

• Pound (lb), and Ounce (oz)

• Kilogram (g), and Liter (L)

Understanding Mass vs. Weight

• Mass is the amount of matter in an object and never changes.

• Weight is the force of gravity pulling on an object.

• An object's weight changes with location, but its mass stays the same.

Multiple Choice

An astronaut travels from Earth to the moon, where gravity is much weaker. Which statement is correct?

• Both the astronaut's mass and weight will decrease.

• Both the astronaut's mass and weight will stay the same.

• The astronaut's mass will decrease, but their weight will stay the same.

• The astronaut's weight will decrease, but their mass will stay the same.

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What Are Metric Prefixes?

• Prefixes are added to a base unit to show its value. Remember with: King Henry Died by Drinking Chocolate Milk.

• Kilo (k) is 1,000 times, Hecto (h) is 100 times, and Deka (da) is 10 times the base.

• A Base Unit, like a meter, gram, or liter, always has a value of 1.

• Deci (d) is 0.1, Centi (c) is 0.01, and Milli (m) is 0.001 of the base unit.

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Multiple Choice

Which metric prefix represents the largest value?

• Milli (m)

• Kilo (k)

• Deka (da)

• Centi (c)

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How to Convert Metric Units

• To convert metric units, we move the decimal point using the “Metric Staircase.”

• First, start at your current unit and count the steps to the new unit.

• The staircase shows the unit relationships, such as: kilo → hecto → deka → base unit → deci → centi → milli, helping you determine how many places and which direction to move the decimal.

• Move the decimal point the same number of places and in the same direction.

• For example, 738.5 cg becomes 0.07385 hg by moving 4 steps to the left.

Multiple Choice

According to the "Metric Staircase" method, how would you convert a measurement from kilometers (km) to meters (m)?

• Move the decimal 1 place to the right.

• Move the decimal 3 places to the left.

• Move the decimal 3 places to the right.

• Move the decimal 1 place to the left.

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Common Misconceptions About Measurement

Misconception	Correction
Mass and weight are the same.	Mass is the amount of matter, while weight is the force of gravity.
Most countries use the Imperial System.	The Metric System is used by nearly every country in the world.
Bigger objects always have more mass.	A small, dense object can have more mass than a large, less dense object.

Multiple Choice

Why is the metric system often preferred for scientific measurements over the imperial system?

• It is a much older system with more history.

• It is based on a decimal or Base 10 system, making conversions simpler.

• Its units are named after famous scientists.

• It has more units for measuring temperature.

Multiple Choice

Which tool would you use to measure the volume of a liquid in a lab?

• Thermometer

• Metric ruler

• Graduated cylinder

• Balance scale

Multiple Choice

A rock has a mass of 200g and a volume of 50 cm³. If this rock is taken to Mars, where gravity is weaker than on Earth, what would you predict about its mass and volume?

• The mass would be less than 200g and the volume would be 50 cm³.

• The mass would remain 200g and the volume would remain 50 cm³.

• The mass would remain 200g and the volume would be less than 50 cm³.

• Both the mass and the volume of the rock would decrease.

Multiple Choice

You measure a length of 5.2 dekameters (dam). Analyze the metric prefixes to determine how you would convert this value to centimeters (cm).

• Move the decimal 3 places to the left, resulting in 0.0052 cm.

• Move the decimal 2 places to the left, resulting in 0.052 cm.

• Move the decimal 2 places to the right, resulting in 520 cm.

• Move the decimal 3 places to the right, resulting in 5200 cm.

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Summary

• The metric system is a global measurement system based on the number 10.

• Mass is the amount of matter in an object, while weight is the force of gravity.

• The base units are the meter (m), gram (g), and liter (L).

• Metric prefixes change a unit’s value, and conversions involve moving the decimal point.

Poll

On a scale of 1-4, how confident are you about converting between metric units?

• 1

• 2

• 3

• 4