Lesson 1: What Powers Your Computer?
This lesson will help students understand that energy comes in
many forms and can be moved and changed from one form to another
but not be created or destroyed. They will learn this as they trace
the steps involved in supplying energy to their community, starting
at their computer and working backwards to arrive at the source
of their electrical energy.
Time Required:
35 minutes
Materials Needed:
A large blackboard or pad; colored chalk or markers
Student Real-World Connections:
Students investigate the sources of the energy they use every day
and begin to understand how their actions have an impact on the
world.
Reproducible Activities:
Try the Make Energy Connections
and Scrambled Energy (PDF) reproducible activities after or
during the lesson: Make Energy Connections challenges students to
draw links between sources, processors, and users of energy; in
Scrambled Energy, students identify energy types as they unscramble
words.
Reproducible Answers:
Make Energy Connections: Four additional progressions (more are
possible) are: 1. sun > tree > fireplace > home; 2. sun
> ancient plants and animals > oil or natural gas well >
electricity-generating plant > cell phone; 3. sun > ancient
plants and animals > oil or natural gas well > refinery >
car; 4. waterfall > electricity-generating plant > stove.
Scrambled Energy: 1. mechanical; 2. solar; 3. electrical; 4. heat;
5. nuclear; 6. kinetic; 7. chemical.
Engaging Your Students:
Similar to a treasure hunt—only backwards—students will
solve the puzzle of the title question and find many surprises along
the way.
Getting Started
You may choose to teach all three sources of energy outlined in
Background Information (scroll down below), or focus on the
source that powers your local lights. (Note: Most plants are fueled
with coal or natural gas. You may choose to call your local utility
to get more information.)
What Students Will Do:
Through careful questions, help your students discover the sources
of energy:
1. Start with the title question: What powers your computer? 2.
For every correct answer (e.g., "electricity"), ask a
question that takes them one step back to the source (e.g., "Where
does electricity come from?"). 3. Continue these questions
until they reach the source. 4. Next, arrange students into small
groups. Have them list other forms of energy they can think of and
trace those to their source. Have each group select one student
to present the results to the class. 5. Finally, have students answer
the following questions based on their discussions:
• Can
energy that did not previously exist be created? (No, the
first law of thermodynamics states that the total amount of energy
in a system remains the same. If you light a wood fire, for example,
you're tapping into the chemical energy trapped in plant matter
and changing it into heat energy.)
• Can
energy be converted from one form to another? (Yes, see Background
Information; see the energy types in bold.)
• Can
energy be moved around? If so, how? (Yes, material rich in
chemical energy can be trucked around, electricity can be sent
through wires, flowing water can be redirected, etc.)
Extension: What Powers Your Home?
Challenge students to discover as much as they can about the energy
used to heat their homes and water. Encourage them to find out what
heats their homes (e.g., heating oil, natural gas, electricity)
and the source. They can ask their parent/guardian for help on researching
how their home is heated; for additional help in researching the
source, they can go on the Web or ask a librarian.
Background Information
The electricity that comes out from electrical outlets undergoes
a long progression before it gets to you. It all starts with a source
of energy that is:
• located,
then
• changed
into a more useful form, then
• transported
to a power plant, then
• transformed
into electrical energy, and finally
• transmitted
through power lines into your home as electricity
Along the way, energy changes forms. But the amount of energy stays
the same, as the first law of thermodynamics requires: Energy
cannot be created or destroyed (though it can be "lost"
by turning into heat or some other hard-to-tap energy form).
The following sections outline the events involved in transforming
the three sources that provide nearly all of America's electricity:
fossil fuels (which provide 71 percent1), nuclear energy,
and hydropower.
Each of these sources and processes have its own set of by-products
that affect the environment. For more information, visit Nuclear
Power and Environment; Environmental
Issues and Mitigation; and Fossil
Fuels.
Fossil Fuels: Most fossil
fuel-powered plants run on coal, while others burn natural gas
or oil. Each of these fuels is formed deep underground when carbon—found
in all living things—is buried and subjected to the heat
and pressure that exist deep below the earth's surface. This process
takes millions of years. Fossil fuels contain chemical energy,
which can be transformed into other energy types.
The steps for getting electricity
from fossil fuel are as follows: 1. Explore earth's surface to
locate fossil fuel supplies. 2. Mine the coal or drill wells to
extract oil or natural gas. 3. Process the fuel into an easily
burnable form. 4. Transport it to a power plant. 5. Burn the fuel
(heat energy) to generate heat that boils water that, most commonly,
lets off steam that turns the turbine (mechanical energy) of an
electricity generator. 6. Send the electrical energy through power
lines. For more information, visit Adventures
in Energy.
Nuclear Power: The steps
in generating electricity from radioactive fuel are as follows:
1. Mine uranium or another radioactive fuel to tap into its nuclear
energy. 2. Process the fuel to enhance its radioactivity. 3. Set
off a chain reaction that splits apart atom after atom of uranium
fuel, releasing nuclear energy that becomes heat energy as it
boils water. 4. Direct the resulting steam toward the turbine
(mechanical energy) of an electricity generator. 5. Send the electrical
energy through power lines.
Hydropower: Hydropower begins
with moving water—either a naturally flowing stream or waterfall,
or a dam system that releases water to fall on demand. The steps
in generating electricity from moving water are these: 1. Direct
flowing water (a form of mechanical energy called kinetic energy)
so that it turns the turbine (mechanical energy) of an electricity
generator. 2. Send the electrical energy through the power lines.
1. Nationmaster.com, "North America: United States:
Energy," www.nationmaster.com/country/us/Energy.
|
Lesson
1: What Powers Your Computer?
