Energy and the Environment Activities: Division I
Activity 1 | Activity 2 | Activity 3
Activity 1: Light a Bulb
Integration Notes:
In this activity, students learn to construct a simple circuit.
They relate their own circuits to those being used in the Nepal
Light Project. This, and further work in Activities 2 and 3,
help prepare the students for the Phase 4 challenge to wire
a model house.
Learner Outcomes:
Students will:
- Recognize the basic requirements for a simple circuit.
- Distinguish between circuits that keep the bulbs bright (parallel)
and circuits that cause the bulbs to dim each time another is added
(series).
- Recognize the effect of using more than one battery in series.
Materials:
For each student or group of students:
- Insulated copper wire with the ends bared (24 to 28 gauge; 2 to 20 cm pieces)
- 3 D-cells
- 3 D-cell holders
- 3 socket holders (the best ones have visible connections to the base and side of the bulb; available from Spectrum)
- 6 pieces of wire with alligator clips on the ends
- 3 mini bulbs
Introduction:
In this activity, students determine the basic conditions necessary
for lighting a single bulb and go on to explore the effects of
extra batteries and of arranging their circuits in different ways.
They are also introduced to the Nepal Light Project.
Activity Instructions:
Caution: Warn students that the wire might get HOT if they leave it attached to a battery.
1. Introduce students to the goals of the Nepal Light Project
(to provide an inexpensive source of light to the people of Nepal).
Tell the students that Dr. Dave Irvine-Halliday is using a
small type of light known as an LED that requires very little
power to light. Introduce the students to their own task, which
is to light a bulb using a single battery and a piece of wire.
Be sure to remind them that although the arrangement of pieces
in the circuit is much the same with Dave's LEDs, his circuits
use much less power, because LEDs require less energy to light
than the bulbs that they will be using.
2. Distribute two pieces of wire, a bulb, and one battery to each
group of students. Challenge them to light a single bulb in as many
ways as they can.
3. After all students have successfully lighted their bulbs, ask them
to suggest steps that are necessary to make this work (e.g. "You have
to touch a wire to the bottom of the bulb."). Encourage other
students to debate ideas that they disagree with. For example,
another student might say that he/she managed to light a bulb
without using a wire attached to the bottom of the bulb (i.e. by touching
the bottom of the bulb directly to the casing of the battery).
Develop a list that all students agree with. It may look something
like this:
a) The bottom of the bulb must be connected to either the positive
or negative terminal of the battery (either by touching the battery
or by connecting it with a piece of wire).
b) The side of the bulb must be connected to either the positive or
negative terminal of the battery (either by touching the battery or
by connecting it with a piece of wire).
c) You have to use the same battery for the positive and negative
connections.
4. Distribute the remaining materials. Challenge the students to
complete the following tasks:
a) Make the bulb brighter.
b) Light two or three bulbs.
c) Light two or three bulbs in a way that makes them noticeably
dimmer each time another is added.
d) Light two or three bulbs in a way that makes all of the bulbs
remain bright when new bulbs are added.
Have the students discuss possible reasons for the observed effects.
5. Introduce the students to the Nepal Light Project.
Ask them how understanding different circuit arrangements could be
important to different lighting applications in this project.
Have them e-mail Dave and his team to find out how their circuits
will be constructed and/or to send any of their own great ideas
to the team.
Extension Ideas:
Discuss the difference between regular bulbs and the LEDs being
used in the Nepal Light Project. Have the students build simple
circuits with LEDs and resistors. There will be more
on this in Phase 4, Division II,
Activity 3. Discuss the advantages of this type of circuit
(more energy efficient, less waste due to disposable batteries).
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Activity 2: An Effective Switch?
Integration Notes:
This activity builds on understandings of basic circuits developed
in Activity 1. It provides important concrete experience that
students may apply as they try to explain circuits in Activity 3,
and provides practical experience with switches that will be useful
as they Wire a Model House in Phase 4.
Learner Outcomes:
Students will:
- Identify a variety of conducting materials.
- Develop a list of criteria regarding what makes an effective
switch.
Materials:
For each student or group of students:
- Various conducting materials (solid and liquid): paper clips,
tacks, paper fasteners, aluminum foil, water, various household
substances that dissolve in water (especially salt), pencil lead,
twist ties, pipe cleaners, other assorted metal and non-metal
objects.
- Assorted building materials; paper fasteners and paper clips are
sufficient for a simple switch, but students may use a variety of
the materials they test to construct different types of switches.
- 1 D-cell
- 1 D-cell holder
- 2 pieces of wire with alligator clips on the ends
- 1 mini bulb
Introduction:
In this activity, students test a variety of different materials
to find out which make good conductors. They use this knowledge
to develop a switch. Finally, they develop criteria to evaluate
the effectiveness of various switch designs.
Activity Instructions:
1. Ask students what more their circuits would need if they were to
be used to wire a house or to power a small flashlight. They may
come up with many ideas! Encourage these, but make sure they
discuss the importance of having a way of easily turning the bulbs
on and off. They may point out that simply clipping the
alligator clip off and on works pretty well, but challenge them
to find another method that does not result in a long piece of
loose-hanging wire (even a small post on to which to clip the disconnected
clip could work as a simple solution).
Another simple solution is to push a paper fastener through one side of a
small piece of cardboard and to fasten a paper clip
(e.g. with a small piece of wire or a piece of pipe cleaner) to the
other end. The paper clip can then be moved back and forth to
open and close the circuit. You may wish to show them this
solution, but encourage them to find a better way.
2. Have the students brainstorm a short list of criteria that they
think would be important for a good switch. They will need to
modify this as they gain more experience with switch building, but
doing this helps provide initial focus. Possible characteristics could
include:
a) Easy to use
b) Durable
c) Easy to build/repair
d) Creative design
3. Ask the students what other materials they might use to construct
their switch. Once they have a list of potential materials, have
them list these in their notebook, test their effect in a simple
circuit, and record their results. Each group should test at
least one liquid (e.g. a glass full of salt water).
4. Have the students use the results of their test to design a
switch. Once they have all developed ideas and started to work on
them, gather the students together to further refine the criteria
they identified in Step 2. For "easy to use", what is excellent?
Good? Not so good? Using their suggestions as a guide, construct
a simple scoring guide that they can use as they continue building
and refining their switches.
5. E-mail Dave's team to see what types of switches they are using and
to suggest useful switch designs.
Extension Ideas:
1. Have the students build a circuit with three bulbs connected
either in parallel or in series. Challenge them to position switches
that allow them to:
turn individual bulbs off and on
turn the entire circuit off and on
2. Discuss the advantages of being able to control the circuit in
this way.
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Activity 3: Electrical Circuits
In our endeavor to understand reality we are somewhat
like a man trying to understand the mechanism of a closed watch.
He sees the face and the moving hands, even hears the ticking,
but he has no way of opening the case. If he is ingenious he
may form some picture of a mechanism which could be responsible
for all the things he observes, but he may never be quite sure
his picture is the only one which could explain his observations.
- Albert Einstein
Integration Notes:
This activity is best performed after students have gained a basic
familiarity with simple circuits in Activities 1 and 2.
It helps them to develop a more detailed understanding of the
working of a circuit and battery, and gives them the opportunity
to test their own ideas.
Learner Outcome:
Students will
develop and test ideas about how and why electrical circuits
function in the manner that they do.
Materials:
- 3 D-cells
- 3 D-cell holders
- 3 socket holders (the best ones have visible connections to the base and side of the bulb; available from Spectrum)
- 6 pieces of wire with alligator clips on the ends
- 3 mini bulbs
Introduction:
In this activity, students develop and test theories regarding why
electrical circuits function in the manner that they do.
Activity Instructions:
1. Ask students what they think is happening in the circuits they
have observed so far. What does the battery do? Why? What makes
the bulb light? Initially, they will likely have responses such as
"Energy from the battery goes into the bulb and makes it light."
Encourage them to go further: Why does it make the bulb light?
What is it doing? Where else do they see light being formed?
Could similar things be happening inside the bulb? Why or why not?
Common responses may include one or more of the ideas in the list
that follows. As ideas are presented, encourage the students to
debate their ideas. When necessary, suggest arguments and/or
possible ways to test students' ideas.
Suggestions for ways to do this are provided for each of the common
responses, although there are undoubtedly many other good ways to
do this (the students will likely come up with some of their own).
None of the ideas presented in the following list is entirely right,
and students will come out of this activity with many questions and
without a definite idea of how a circuit works. However, their
ideas typically prompt them to test many different circuit
configurations and to consider the inner workings of a battery
and circuit in much more depth than they otherwise would.
Complex understanding of the actual workings of a battery and/or
circuit is unnecessary at this point.
Common Theories and Ways to Challenge Them
Crashing Current (Positive and negative energy from the
battery crash in the bulb and cause it to light.)
If this is true, can you light a bulb with the positive end of
one battery and the negative end of another?
(No) Why or why not? (One group suggested that the current has
nowhere to go in this arrangement, because it is "packing" when
the circuit is hooked up in this manner. They reasoned that
adding a second wire between the other positive and the other
negative might provide a type of "outlet valve" that could e
liminate what they referred to as "packing" in the battery.
They tried it. It worked. Why?)
If current crashes in the bulb, what happens when you connect
two bulbs in a chain (in series)? How can it crash in two separate
bulbs when it has to go through one to get to another?
One-Way Current; Electricity Used Up in the Bulb
If the electricity is all used in the bulb, do you need a second
wire to the other side of the battery?
Can electricity really be "used up"? How? If it burned up in
the bulb would there be bits left (e.g. "burned stuff")? If so,
why don't you see burned pieces piling up in the bulb?
One-Way Current; Electricity Returns to Battery
("Particles"
travel through the tiny wire in the filament of the bulb and create
heat and light as they "squeeze" their way through.)
If the particles return to the battery unchanged, why do
batteries ever run out?
Two-Sided Battery
("Positive energy" stored in the positive
side of the battery is changed in the circuit and re-enters the
battery on the other side as "negative energy." When all of the
positive energy is used up, the battery is dead.)
If batteries have two separate sides, how does "good" energy get
through the "bad" side of another battery when two batteries are
hooked up end to end (in series)?
In fact, certain aspects of each of these theories are accurate and
others are false. Current travels in a single direction and
batteries do not have dividers (although the positive and negative
sides are separated by the types of chemical reactions that take
place at different places in the battery - one side gives up
electrons, while the other side accepts them).
Students have a difficult time imagining how "electricity particles"
can travel through a circuit unchanged and return to an undivided
battery where they cannot be used again. If their arguments begin
to go in circles around this issue, summarizing it for them in
this manner sometimes helps them to generate potential solutions.
Although the students will not develop a complete model of a battery
or a circuit in this activity, their ideas prompt the investigation
of various implications of their ideas that they may otherwise not
have thought to test and that would likely not have had particular
significance if they had.
2. Have the students read the background material on the
Nepal Light Project.
Discuss how electricity made by generators relates to their ideas.
Discuss the advantages of a hand-generator: e.g. (a) it doesn't
run out of energy and (b) it doesn't have harmful chemicals that
pollute the soil.
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