Thermal Energy

THERMAL ENERGY

Different objects at the same temperature can have different energies. Thermal energy is the total energy of all the molecules in an object. The thermal energy of an object depends on three things: 

• the number of molecules in the object 

• the temperature of the object (average molecular motion)

• the arrangement of the object’s molecules (states of matter). 

The more molecules an object has at a given temperature, the more thermal energy it has.
For example, a large bucket of water at 25^oC has more thermal energy than a small glass of water at 25^oC.



Now if the temperature is different but the amount of molecules is the same, the object with the higher temperature has more energy.
For example, an 8 oz. glass of boiling water has more thermal energy than an 8 oz. glass of cold water. 

Multiple Choice

Which has more thermal energy, 5.0g of solid candle wax or 5.0g of liquid candle wax if they have the same temperature?

• the solid wax

• the liquid wax

• they have the same

Multiple Choice

Which has more thermal energy, 5.0g of solid candle wax or 15.0g of solid candle wax if they have the same temperature?

• the 15.0g sample

• A the 5.0g sample

• they have the same

Multiple Choice

What energy change must happen for a gas to condense to a liquid?

• decrease energy

• increase energy

• more information is needed

Multiple Choice

If substance one and substance two are at the same temperature, which one has more thermal energy?

• substance one

• substance two

• More information is needed.

• They have the same energy.

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Thermal Energy
Lesson 1.2: Investigating Hot and
Cold

Multiple Choice

These diagrams represent the molecules of a sample. Which sample is “hotter” than the other as based on your interpretation of the diagram and your knowledge of how temperature, speed, and kinetic energy are related.

• Sample A

• Sample B

Multiple Choice

These diagrams represent the molecules of a sample. Which sample is “hotter” than the other as based on your interpretation of the diagram and your knowledge of how temperature, speed, and kinetic energy are related.

• Sample C

• Sample D

Multiple Choice

The average kinetic energy of the molecules that make up Sample E is

• 3

• 4

• 5

• 36

Multiple Choice

The average kinetic energy of the molecules that make up Sample F is

• 2

• 3

• 4

• 27

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Activity 1

Thermal Energy: Lesson 1.2

Today, we will begin a new unit called Thermal
Energy.

You will start with a Warm-Up each day to get
you thinking about science ideas. You can
begin working on it independently as soon as
you come in.

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Thermal Energy
Warm-Up

5 MIN

Thermal Energy: Lesson 1.2

Multiple Choice

1. Temperature is the measurement of how hot or cold something is.

• Agree

• Disagree

Multiple Choice

When something heats up, it moves faster, and when something cools down, it moves slower.

• Agree

• Disagree

Multiple Choice

When something heats up, new energy is created, and when something cools down, energy is destroyed.

• Agree

• Disagree

Multiple Choice

Hotter things have more energy than colder things.

• Agree

• Disagree

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Activity 2
Introducing the Unit

10 MIN

Thermal Energy: Lesson 1.2

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Unit Question

Activity 2

Thermal Energy: Lesson 1.2

Why do things change temperature?

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Activity 3
Investigating Hot and
Cold Things

25 MIN

Thermal Energy: Lesson 1.2

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Today, we will investigate this question:

Activity 3

Thermal Energy: Lesson 1.2

Investigation Question:
How is something different when it is warmer or cooler?

Open Ended

When you’ve just taken a stick of butter out of
the fridge, what is it like? What are some of its
properties? What about after you’ve let it sit at
room temperature for 20 minutes and get
warmer?

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Activity 3

Thermal Energy: Lesson 1.2

The Investigation Question asks how
something is different when it is warmer or
cooler because you’ll be thinking about how different things change temperature. In this unit, you’ll also start to think about what is happening to something’s molecules when it gets warmer or colder.

Open Ended

What are some other examples and ideas
about how things are different when they are
warmer or cooler?

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Activity 3

Thermal Energy: Lesson 1.2

Today, you will
investigate how warm
water is different from
cold water. You’ll watch a video to see what happens when you add food coloring to a cup of hot water and a cup of cold water.

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Investigation Notebook pg 8

Activity 3

Thermal Energy: Lesson 1.2

You’ll record the
temperatures and your
observations.

Before you start, you’ll
also make a prediction
about what you think will
happen.

Investigating Hot & Cold Water

Click on the link below to watch the demo

https://www.youtube.com/watch?v=ghi3Z_XtEa8

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Activity 4
Reflecting on the
Investigation

5 MIN

Thermal Energy: Lesson 1.2

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Activity 4

Thermal Energy: Lesson 1.2

At the end of most lessons in this unit, there
will be a reflection question or activity that will
help you summarize the science ideas you
have learned.

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Activity 4

Thermal Energy: Lesson 1.2

Investigation Question:
How is something different when it
is warmer or cooler?
Today, you’ll reflect on
the initial ideas you had
about this question and
consider how the results
of the hands-on
investigation confirmed
your thinking or made
you change your mind.

Open Ended

How did the experiment with the cold and warm water change your thinking about the Investigation Question, How is something different when it is warmer or cooler?

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Thermal Energy
Lesson 1.3: Temperature and
Motion

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Activity 1
Warm-Up

10 MIN

Thermal Energy: Lesson 1.3

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Activity 2
Simulating Hot and Cold
Water

25 MIN

Thermal Energy: Lesson 1.3

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Activity 2 - Screen 1

Thermal Energy: Lesson 1.3

Throughout this unit, we’ll
use the Sim you just
explored.

This Sim is a digital
model that will help us
learn about how
temperature can change.

Multiple Choice

What do you think the
small circles in the Sim
represent?

• water

• molecules

• buttons

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Vocabulary

Thermal Energy: Lesson 1.3

a group of atoms joined together in a particular way

molecule

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.3

Throughout the year, you
can look up vocabulary
words in the glossary to
help you understand
what they mean.

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.3

In this unit, we will
describe the smaller
pieces that make up stuff
by using the word
molecule.

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.3

In the Sim, each circle
represents one molecule.

The Sim portrays
molecules on a much
larger scale than their
size in real life.

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.3

The Sim shows a small
number of molecules so
we can easily observe
what is happening to
them. The things around
us—even very small
things—are made up of
billions of molecules.

Activity 2 - Screen 2

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Key Concept

Thermal Energy: Lesson 1.3

1. Things are made of molecules (or other

types of atom groups).

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.3

Now, you’ll use the Sim to
model the food coloring
investigation. This will
help you find evidence to
help explain why the food
coloring spread out
differently in the two
water samples.

Activity 2 - Screen 3

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Investigation Notebook pg 12

Activity 2 - Screen 3

Thermal Energy: Lesson 1.3

Open Ended

What do you notice about the movement of the molecules of the two samples?

Open Ended

Explain what you discovered from the Simulation about why food coloring spreads faster in warmer water. You can also think back to the Glow Stick Lab. It is the same concept, just different

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Investigation Notebook pg 13

Activity 3

Thermal Energy: Lesson 1.3

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Multiple Choice

Which image shows the difference between the speed of molecules in hot and cold water?

• A

• B

• C

• D

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Key Concept

Activity 3

Thermal Energy: Lesson 1.3

2. When a thing gets hotter, its molecules are

moving faster.

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Key Concept

Activity 3

Thermal Energy: Lesson 1.3

3. When a thing gets colder, its molecules are

moving slower.

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Activity 4
Homework

Thermal Energy: Lesson 1.3

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Activity 4

Thermal Energy: Lesson 1.3

For this activity, you will
read an article about absolute zero to learn more about temperature and molecular speed. Then, you’ll answer some
questions about it.

​Absolute Zero



You’ve probably felt cold temperatures at some time in your life. Maybe you live somewhere with cold, snowy winters...or maybe you’ve just opened the freezer to grab a popsicle on a warm day! The temperature inside a normal kitchen freezer is around –18 degrees Celsius (0°F), but there are temperatures that get much colder than that. The coldest outdoor temperature ever recorded on Earth is –94.7°C (–135.8°F). In space, things get even colder: scientists have measured temperatures as low as –270°C (–454°F) there.

We know that the temperature outside can feel warm or cold to us, but what is temperature actually telling us? Temperature is related to the average speed of the molecules of an object or material. Molecules are constantly moving around. When an object's molecules move at faster speeds, the object has a higher temperature. When an object's molecules move at slower speeds, the object has a lower temperature.

Is there a limit to how cold things can get? Yes! This is because temperature is determined by average molecular movement, and there is a limit to how slowly something can move. After all, if something slows down completely, it just stops moving.

What would happen if the molecules in a sample stopped moving entirely? If none of the molecules were moving, then the average speed of the molecules would be zero. This means that the sample would be at absolute zero, a temperature of –273.15°C (–459.67°F). Absolute zero is the coldest possible temperature—the temperature at which there is absolutely zero molecular movement. Scientists realized over 350 years ago that absolute zero could exist, but nobody has succeeded in demonstrating it. It may not be possible to reach absolute zero, but that hasn’t stopped scientists from trying.

Multiple Choice

Which of the following would be true if something was at absolute zero?

• The molecules that make up a sample wouldn’t be moving.

• The molecules that make up a sample would be moving very slowly.

• The molecules that make up a sample would be moving very fast.

Multiple Choice

If the molecules of a sample speed up, what else happens?

• The temperature of the sample decreases

• The temperature of the sample increases.

• The temperature of the sample stays the same.

Multiple Choice

Is there a limit to how cold things can get?

• Yes, there is

• No, there is not.

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Thermal Energy
Lesson 1.4: Molecules and
Temperature

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Activity 2
Redefining Temperature

15 MIN

Thermal Energy: Lesson 1.4

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Key Concept

Thermal Energy: Lesson 1.4

4. Temperature is a measure of the average

speed of the molecules of a thing.

Activity 2 - Screen 1

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Thermal Energy: Lesson 1.4

We are going to have to find the average
kinetic energy of molecules in a thing, which
will tell us its temperature.

Since we are just starting to learn about
averages, let’s practice finding an average
using a more common example: how many
pets people in our class have at home.

Activity 2 - Screen 1

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Thermal Energy: Lesson 1.4

An average is a single number that tells you
something about what’s typical of a larger set
of numbers.

Averages are helpful because they allow us to
compare groups of different sizes without
having to think about each individual member
of the groups.

Activity 2 - Screen 1

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Vocabulary

Thermal Energy: Lesson 1.4

a number that summarizes a set of data and that can be

computed by adding all the numbers in a list and then dividing

by the number of numbers in the list

average

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.4

In this unit, you will be
using the idea of an
average to think about
differences in
temperature.

Activity 2 - Screen 2

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Thermal Energy: Lesson 1.4

Next, you’ll look at two
diagrams that show
things made of
molecules moving at
different speeds and
calculate the average
speed of the molecules
in both diagrams.

Activity 2 - Screen 3

Multiple Choice

The average speed of the molecules in Diagram 1 is

• 2

• 3

• 5

• 10

• 30

Multiple Choice

The average speed of the molecules in Diagram 2 is

• 2

• 3

• 5

• 10

• 30

Multiple Choice

What can you tell about the temperature of the things in these diagrams by calculating the average speed of the molecules?

• The thing in Diagram 1 has a higher temperature than the thing in Diagram 2.

• The thing in Diagram 2 has a higher temperature than the thing in Diagram 1.

• The things in both diagrams have the same temperature.

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Activity 3
Modeling Differences in
Temperature

20 MIN

Thermal Energy: Lesson 1.4

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Activity 3

Thermal Energy: Lesson 1.4

Remember, scientists create models to help
them explain concepts to others and to clarify
their own thinking about a concept.

Models are especially helpful in explaining
things like molecules that cannot easily be
observed in daily life.

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Activity 3

Thermal Energy: Lesson 1.4

You will use this
Modeling Tool to help
you understand what happens when the air or temperature of something gets warmer

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Activity 3

Thermal Energy: Lesson 1.4

Don’t worry about
modeling a realistic
number of molecules.
Real things are made of
billions of molecules,
which is impossible to
draw. Just include five or
six.

Investigation Notebook pg 19

Draw

Create a model that shows the difference between warmer air and cooler air. Be sure to include equal numbers of molecules in each box.