By Sarah Carrier and Ted Rex
M
any science concepts are too large, too small,
or too far away for direct observation, and
electricity is one elementary school subject
that is both complex and invisible, thus encouraging the use of models and inference. The following activities can help students in fifth grade and beyond
begin to build a base for learning about electricity in a
“hands on/minds-on” fashion.
Materials:
• 2 drinking glasses of the same size
• 1 bottle of clean water for drinking
• 2 straws: a thin straw (such as a stirring straw) and a
wider one (such as a large drinking straw) of the same
length. Another option is to have two straws of the
same diameter but one about 4–5 cm longer than the
other.
• 1 piece of nylon rope (with ends taped together to
form a loop) long enough for all the students to hold at
the same time. Plan on about ½ –1 meter of room for
each student (clothesline rope is perfect)
36 Science and Children
• Signs labeled battery, switch, and bulb
• Class sets for small group investigations consisting
of (all compatible): 1 C cell battery, 2 insulated wires
with insulation stripped from ends of same size and
length, switch, and flashlight bulb.
Engage
Introduce the lesson by telling students that they will
be learning about electrical circuits. Ask students what
they know about electricity as a diagnostic assessment of
students’ prior knowledge. Accept all student ideas and
refer to students’ concepts throughout the lesson. Provide each group of three students with a battery, bulb,
and wires to allow discovery time. After about five minutes, challenge students to light the bulb. Some groups
will be successful, and this activity will provide an initial
experience with closed circuits to complete the path of
electrons. Discuss designs that resulted in lighting the
bulb. Introduce the concepts of energy source (battery),
electrons, and closed circuit. Ask the students to consider what is happening in the battery and wires system
It is important to be able to concentrate energy
so that it is available for use where and when it is
needed. For example, batteries are physically transportable energy storage devices, whereas electricity
generated by power plants is transferred from place
to place through distribution systems (NRC 2012,
p. 129).
The following model provides students with a model
for this transfer of energy and can support students’
experiences with the battery, wires, and bulbs.
Explore
Take a soft nylon rope with the ends taped together, and
have the students hold the rope to form as large a circle
as your rope will allow. Explain to them that this closed
circle of rope in their hands represents a circuit. With the
rope in their hands, show the students that our rope is
Photographs courtesy of the authors
that can make the bulbs light. Many of our students responded that the battery sends its power to light the bulb
through the wires.
Describe the role of electrons, discovered in 1897,
flowing from the positive terminal of the battery to the
negative terminal. Reinforce the idea that the battery
stores the energy and has the potential to send electrons
flowing through the wires, but until the circuit is complete
the electrons do not flow.
In order to model the meaning of potential energy, hold
a ball of clay above your head and drop it. Continue doing
this, and ask the students why the clay falls when you let
it go. Many students respond that gravity is causing the
clay to fall to the ground. Lift the clay again, and as you
hold the clay above your head, point out that when you
release it, the movement of the falling ball is clearly seen,
but before you let go, it has the potential to move. The
potential energy within the clay changes to kinetic energy
when the clay is released. The principles of potential
energy differences between the two ball positions help
model the differences that allow electrons to flow through
a circuit. As soon as the circuit is complete, the potential
energy in the battery allows the electrons in the wires to
flow. Provide students a second opportunity to light their
bulb. Student-to-student discourse followed by the sensemaking discussion and scaffolding by the teacher combine
to help students visualize the need for closed circuits in
lighting the bulbs. Switches can be introduced in a second
attempt of lighting bulbs, further reinforcing the electron
flow and closed circuits. Relating switches to home light
switches will further connect to students’ lives.
Disciplinary Core Idea, PS3.D of A Framework for
K–12 Science Education states that by the end of grade 5
students should understand:
The student representing a battery joins the circuit.
not moving; we have no electrons flowing. Encourage the
students to infer from their previous investigations what
the circuit needs in order to get the electrons flowing.
Some students will recognize that a battery or some other
energy source is needed.
With the need for a battery understood, make one
student the battery by attaching a label to him or her that
reads “battery.” Have that student begin to pull the rope
while other students, holding the rope loosely, allow the
rope to pass through their hands without any restrictions.
Have the students hypothesize why the battery is causing
the current flow (electrons), presenting an opportunity for
student discussions that will help the teacher formatively
assess students’ understandings. This allows you to identify early on whether the students (1) are able to name the
energy source as having potential for the flow of electrons,
and (2) understand that the closed circuit completes the
energy flow. Introduce labels to two more students, the
“switch” and the “bulb.” Have
the student who is the bulb open
his or her eyes and mouth wide
to represent a lit bulb as the rope
flows and the circuit is closed.
Take turns removing the battery Keywords: Current electricity
or having the SWITCH student www.scilinks.org
open the switch (by removing Enter code: SC031301
March 2013 37
With the “battery” working, take this opportunity to
explain how the battery is not creating the electrons
within the circuit. This is a common misconception.
The electrons in the circuit exist inside the wire, not the
battery. Students love their roles as electrons in the wire
because they all contribute and experience the model of
energy flow. Students can quietly hum to represent their
role as electrons and stop humming when the battery is
removed or the switch opened. Stand in the middle of
the circle, asking questions such as, “Why is the energy
flowing?” and “What happens to the energy when the
circuit is interrupted?” Relate the demonstration with
the clay ball’s potential energy to the electrons and battery in the rope model.
As long as there is an imbalance of positive and negative
charges, electric current will occur. Electric current cannot
flow through a circuit unless there is voltage present to
create a difference in energy potential. As long as there is
energy source providing voltage and the circuit is closed,
the electric current will flow. The rope model helps
students visualize electric current and flow.
The student with the wide straw should, naturally, finish first. Ask the students why the person with the wider
straw won the contest so easily. All students have clear
ideas as it seems to be due to straw diameter. Ask students
if electric wires are all the same width and length. You can
also use this opportunity to help students learn about fair
tests by discussing how the diameter of the straw influenced the flow, and ask students to describe other factors
that would influence the fairness of the test. Point out that
their clear ideas about the winner were inferences since
they used both their observations and their prior knowledge.
Be sure to ask students to explain why the wider straw
helped the contestant. This helps students begin to build
their mental models of factors that influence the flow of
electric current. Help the students recognize the concept
of flow and restriction of flow. These concepts connect to
the sizes of cables and wires used in energy distribution in
an electric system. Resistance can be modeled in the rope
activity by having one student serve as a “resistor” and
impede the rope’s movement by tightening his or her grip
on the rope. Resistors are anything that electricity cannot
easily pass through, in contrast to a conductor. Conductors
have low resistance and insulators have high resistance.
The plastic handle on a metal spoon resists the transfer
of heat that passes easily in the metal spoon. See Internet
Resources for more information on resistors. Elaborate
Evaluate
the tape on the rope) and the bulb should close his or her
mouth and eyes as the electron flow ceases in an open
circuit or without an energy source.
Explain
An extension to learning basic electricity flow is to introduce resistance. Ask if students have noticed electric wires
of different sizes ranging from high-voltage overhead
cables to smaller extension cord wires. Describe the role
of transformers decreasing the electricity to smaller household wires. Transformers transform or change electricity
levels, usually from high voltage to lower voltage. Household appliances cannot use the high levels of electricity
that travel long distances on high voltage wires, so transformers are used to “step down” or decrease the power.
See Internet Resources for more about transformers.
Solicit student ideas about the size of the wires and their
effect on the flow of electricity. Tell them that you want to
have a contest. Select two students to come forward to be
contestants. Have two clean, equal-size glasses with the
same small amount of water (about 100 ml) on a table next
to the students. State that whoever can drink their glass of
water first wins the contest. Tell them to begin when you
count to three. Count out loud “one… two…” and then
stop and tell them that you forgot one thing: they need to
drink the water with straws. Using new straws, hand one
of the students a thin straw and the other a much wider
straw. Apologize for the mistake (students will eagerly
begin figuring out who is going to win the contest) and
count to three.
38 Science and Children
During the rope activity, the students will be circled
around the teacher, allowing for constant formative assessment. By soliciting students’ developing ideas, we
can identify and address potential misconceptions as
students relate the rope model to their experiences with
wires and bulbs. As a summative assessment, ask students to draw and label models of an electric circuit in
their science notebooks. The exploration and discussion
Why does water flow more quickly through the wider straw?
Learning the Ropes With Electricity
Trade Books
Bailey, J., and M. Lilly. 2004. Charged up: The story of
electricity. Minneapolis, MN: Picture Window Books.
Fairley, P. 2008. Electricity and magnetism. Minneapolis, MN:
Twenty-first Century Books.
Glover, D. 1991. Batteries, bulbs, and wires. New York:
Kingfisher Publications.
Kamkwamba, W., and B. Mealer. 2009. The boy who
harnessed the wind. New York: Harper Collins.
Internet Resources
Exploring flow and resistance with a drinking straw contest
from the “Engage” section introduced students to the
presence of electrons and the positive and negative terminals of the battery, which relates to PS1.A: Structure
and Properties of Matter of Core Idea PS1: Matter and
Its Interactions in A Framework for K–12 Science Education (NRC 2012). Students should label the battery as the
energy source that allows movement of the electrons in
the wires, identify the direction of flow from positive to
negative, and label closed and open circuits.
Modeling Makes Abstract Concrete
Electric current flow is a complex topic that should be
approached from multiple perspectives that allow the
students to relate to this new topic with concepts they
already understand at an intuitive level. These activities
help students learn about models and images in science
and address the crosscutting concept of energy and matter: flows, cycles, and conservation from A Framework for
K–12 Science Education (NRC 2012). Providing students
with concrete images to model abstract concepts allows
for student engagement and interaction with physical
science big ideas. n
Sarah Carrier ([email protected]) is an assistant professor at North Carolina State University in Raleigh, North Carolina. Ted Rex ([email protected]) is an
elementary school teacher at Poe Montessori School in
Raleigh, North Carolina.
Reference
National Research Council (NRC). 2012. A framework for
K–12 science education: Practices, crosscutting concepts,
and core ideas. Washington, DC: National Academies
Press.
Electrical energy transmission and distribution
www.iec.ch/about/brochures/pdf/technology/
transmission.pdf
Modeling electric current with a rope (video)
www.youtube.com/watch?v=uyikV_sV7ZQ
Resistors
www.qrg.northwestern.edu/projects/vss/docs/thermal/3whats-a-resistor.html
www.explainthatstuff.com/resistors.html
Science Hobbyist: Teaching kids electricity
http://amasci.com/miscon/elteach.html
Transformers
www.energyquest.ca.gov/how_it_works/transformer.html
http://edisontechcenter.org/Transformers.html
Resources
Gibilisco, S. 2005. Electricity demystified. New York: McGraw Hill.
Parker, S. 2005. Eyewitness electricity. New York: D.K
Publishing.
Wainwright, C.J. 2000. Prentice Hall science explorer:
Electricity and magnetism. Upper Saddle River, NJ:
Prentice Hall.
Connecting to the Standards
This article relates to the following National Science
Education Standards (NRC 1996):
Teaching Standards
Standard D: Teachers of science design and manage
learning environments that provide students with
the time, space, and resources needed for learning
science.
Content Standards
Grades 5–8
Standard B: Physical Science
• Transfer of energy
National Research Council (NRC). 1996. National
science education standards. Washington, DC:
National Academies Press.
March 2013 39