In this issue of CoolStuff, I would like to
expand on the Concept Development stage of the Learning Cycle. From the last
issue of CoolStuff, many of
you know the
Learning Cycle is an
approach to science instruction developed by Atkin and Karplus in 1962.
This approach puts the phenomena first. Names and numbers are brought
into the picture only after students are allowed direct contact with the
phenomena. Although there are a number of variations on the theme, the
essential learning cycle consists of three phases. These phases
include exploration, concept development and application. In this issue I
would like to cover some of the aspects of the Concept Development
here to download a pdf file of the complete Learning Cycles article.
During concept development, basic
principles emerge, terminology is introduced, and mathematical relationships
are derived. With the teacher serving as a guide, students construct
meaning from observations made during the exploratory. How is this
I generally engage students in class
discussion immediately after their exploratory activities. At this point,
students have a need to know and are motivated to talk about what they have
just encountered in the lab. This discussion is most effective when it is
student-centered with the teacher serving as a facilitator, not as a
dispenser of knowledge. The goal of the process is to have meaning and
understanding emerge from conflicting ideas about the phenomena.
While it is desirable for students to drive
the discussion regarding the phenomena encountered during the exploration,
it is the teacher who must develop a mechanism for introducing terminology
and mathematical relationships. Sometimes another activity is the answer.
The written instructions for the activity can introduce students to formulae
and terminology as well as provide them with instructions for carrying out
the experiment. Such a lab may be used to acquaint students with the needed
terms and equations in a very natural and engaging way. A subsequent
discussion, video and worksheet may then be used to conclude the concept
An activity from my energy learning cycle
illustrates this approach. I use the time-honored “student power lab” because it presents
terms and concepts in a meaningful
context. The lab sheet not only provides students with instructions for
carrying out the experiment, but also introduces them to the vocabulary,
formulae and units relating to work, power and energy. In the experiment
students determine the power they develop running or walking up stairs.
They calculate the work they do by multiplying their weight by the vertical
distance traversed. Dividing the work by the time of ascent yields power.
The goal: students assimilate key concepts by using them.
Of course a variety of methodologies may be
employed during the concept development stage of the learning cycle. They
include reading, computer work, video clips or demonstrations.
following quote from physics teacher Tom Kozikowski provides an example of a
highly effective approach to bridging the exploratory and concept
development phases of the cycle.
“The first two portions of the learning
cycle were terrific. The students were engaged and really thinking deeply
about the physics concepts. As a homework assignment after the exploration,
before we had any class discussion or any readings on Newton's Laws, I asked
the students to state each of Newton's Laws in their own words and then to
support their statement with evidence from the activities. Although few
students stated the Laws as soundly as Newton himself, I was very proud of
the conclusions they developed and the support they provided. The students
and I have found this learning cycle to be excellent!!!”
Learning Cycle Exploratory
type of food never ceases to amaze students. They have always heard that
the food we eat provides our bodies with energy, but they never think that
the energy stored in a single sugar cube could be transformed into so much
heat and light. We’ve had kids burn everything from peanuts to dried out
a) Place a piece of food on the tip of a dissecting needle
or in a paper clip. Now light
the food on fire.
Measure the time it takes for the food to burn.
type of energy does burning food produce? What is the source of this
c) Select two different food samples of
comparable size. Which do you think will burn longer? Burn the two samples
separately and compare the length of the burn. What did you observe about
the energy content of the two samples?
Student shown here burning a potato chip using a home-made
calorimeter. For info on making your own calorimeter click the image .
Compress one of the “poppers”. Do
you do work compressing the elastic material?
b) What becomes of the work you did?
c) Describe the energy transformation(s) that occur when the toy jumps.
d) What becomes of the popper’s energy once it has come to rest on the
Station 2 Potent
An inexpensive toy, called the “popper” allows students to investigate a
variety of energy transformations.
Initially work is done in deforming the popper. When the popper abruptly
returns to its original shape, its elastic potential energy is transformed
into kinetic energy and then gravitational potential energy and then back
into kinetic energy.
The popper may also be used to demonstrate activation energy. Note that when
dropped from a low height, a small amount of activation energy results in
the release of considerably more energy.
….enter another station and
image the amazing
smashing steel spheres! These 2-inch, 1 pound ball bearings clearly
demonstrate the eventual fate of most forms of energy. Smelling a piece of
paper placed between colliding spheres reveals that the kinetic energy
possessed by the moving spheres has been converted into heat.
A rather impressive variation on this
experiment can be done with the Newtonian Demonstrator, if you happen to have
one. Try it with a small piece of flash paper!
a) Place a piece of paper between the two
spheres. Now smash them together. After the spheres collide, smell the area
on the paper where they came into contact. What do you detect? What do you
suppose caused this odor?
b) Did the paper get hot? That is, where did the energy come from that was
responsible for the heating? As best you can, describe the energy
transformation that took place as a result of the collision.
b) Examine the point of contact. Do you observe any signs of scorching on
the paper? What can you conclude about the increase in the paper's
temperature? In theory, what could you do to cause combustion?
The Forever Flashlight
Station 4 Crank it Up...
The Don Rathjen’s “Forever Flashlight”
permits students to see how mechanical energy may be transformed first into
electrical energy and then into light. Five disk magnets sliding through a
coil of wire light an LED coming and going. Variations on this theme include
the “Nightstar Flashlight” and
a) While holding the Forever Flashlight in
your hand, note the LED. Now shake it so that the magnets slide back and
forth through the tube. What did you observe?
Purpose an explanation for your observation?
What energy transformations does this device illustrate?
Station 5 More Power! er er er..
station can actually be broken up into a number of events based on your
Genecon hand-operated generator takes this concept one step further. It is
versatile, easy to use, and provides students with a kinesthetic learning
experience. Mechanical energy may be transformed into a variety of forms.
These include heat, light, sound, motion and electrical potential
energy. We use old miniature Christmas tree lights, transistor radios,
one-Farad capacitors, and a liquid crystal thermometer attached to
a 5-ohm power resistor and the toy train you see on the right.
Students love to connect two generators together. They learn about the
motor-generator principle without being told. Paraphrasing Eric Rodgers:
“you can’t tell which is agent and which is victim.” By counting the number
of turns of the motor unit produced by 10 turns of the generator, it
is possible to determine the efficiency of the generator-motor system.
Obtain a Genecon hand-cranked generator. To see if yours is functioning
properly, you may check it by connecting the two clips attached to
the Genecon's leads to a small light bulb. What happens when you turn the
crank clockwise? What happens when you turn the crank in the opposite
Adjust the rate at which you turn the crank. What happens when the crank is
turned rapidly? turned slowly?
Describe the energy changes taking place when you light the bulb.
Connect your generator to the resistor/heat sensor device. Turn the crank
rapidly for a fairly long time and watch the thermometer strip. What
happens? Describe all the energy changes taking place.
Connect your generator to a capacitor. Turn the crank for a minute or two
and then let go of the generator handle. What happens?
Recharge the capacitor and quickly disconnect it from the generator. Now
connect the leads to one of the light bulbs. What do you observe? Discuss
the energy transformations taking place.
Connect your generator to another generator and turn the crank. What do you
see? Describe the energy changes that are taking place.
Now line the two generators up with both of their handles pointing straight
Turn the generator ten times while your partner counts the number of turns
made by the Genecon that is serving as a motor. Calculate the efficiency of
the two Genecon system. (Note: the efficiency of the generators is equal to
the number of turns of the motor divided by the number of turns of the
For more information on the Hand
Battery, click the image to visit The Exploratorium
Teacher's Note: Sweaty hands will increase the
meter reading. You might have a student exercise first then check the
Station 6 The Human Touch
The hand battery uses copper and aluminum
plates connected to a galvanometer. An electric current is produced by
placing your hands on the plates.
a) Examine the “Hand
Battery.” Describe the construction of this device as best you can.
Use a sketch if necessary.
b) Observe the meter while you place your hand
on the adjacent copper and aluminum plates. What did you observe?
How do you suppose this device works?
Try pressing down harder on the plates. Did this alter the meter reading?
Why? What energy transformations do you suppose is taking place?
d) Compare your meter reading, with a friends.
Station 7 You Light up my Life
You have no doubt seen the Radiometer many
times. However students always seem to find the concepts of this simple device
fascinating as well as baffling.
Examine the radiometer (glass bulb with four rotating vanes.) Now bring a
light bulb close to the Radiometer (approx. 10cm.). What did you observe?
Examine the radiometer
closely. What is the direction of movement? Which colored side of the vanes
c) Can you explain the operation of the
Radiometer based on the direction of rotation of the vanes?
d) Predict what would happen if the light
source was moved closer or farther away? Test your predictions.
The Rubber Band Machine
Singapore Science Center Energy Exhibit
Station 8 The
Heat is On!
rubber is a substance which can stretch many times its original length.
During extension, rubber gives off heat and as it contracts it absorbs heat.
In addition, when a stretched rubber is heated, it contracts. This property
of rubber is used in the rubber band machine on the left. The infra-red lamp
heats up the rubber bands nearest to it, causing them to contract. The
contraction causes the center of gravity of the wheel to shift towards the
lamp, and the wheel becomes unbalanced and turns.
Use a large size rubber band for this next
station, a smaller one might break and snap the "Cheek'ee" in the face!
a) Pull or stretch a rubber band or balloon as you hold it up to your cheek.
Describe how it feels.
b) While holding it to your cheek, allow it to contract quickly. How does
the rubber band feel now?
Getting Juice from Juice
Using a knife, make two small slits in the surface of a lemon, potato or
apple. You can use metal strips or coins, key is to use dissimilar
metals. After cleaning the outer surfaces of a dime and penny (or metal
sandpaper, insert the coins in the slits. Note: a short length of copper
pipe (any diameter) and a galvanized nail also work well.
a) What happens
when the galvanometer leads are touched to the outer edges of the coins or
pieces of metal?
b) Increase, and then decrease, the depth to which the coins (or metal) are inserted
into the fruit. Do you detect any change in the galvanometer reading as you make
Why do you suppose this happens?
c) You can increase the voltage produced by this simple electrical device by
connecting a number of the lemon cells together in series. This means that
you connect a penny in one cell to a dime in another cell until all cells
are connected. When you finish making these links, connect the coins at each
end of the chain (a penny at one end and a dime at the other) to the
galvanometer. What happens? Try using four or five cells in series to
light a small light bulb or red LED (light emitting diode).
Basking in the After Glow
The main component of this station is a large
piece of pink insulation foam covered with a sheet of phosphorescent
material. The station can be set up two different ways. In the first version
the screen is placed in a totally dark area. A person is directed to stand
close to the phosphorescent screen, select a pose, and have a partner
trigger an electronic flash unit. When the person moves away from the
screen, the area touched by the light of the flash glows an eerie green. An
Image of the person remains on the screen as a shadow. The shadow lingers on
the screen for several moments.
Another way to use this idea is to illuminate the phosphorescent screen with
a black light causing the whole screen to glow. A person stands near the
screen blocking out the black light and casting a shadow on the screen. When
the person moves, his image remains on the screen. The shadow does not last
as long as in the first version, but this set-up eliminates the need for
complete darkness and an electronic flash.
Energize the phosphorescent screen with a bright light source. What happens when
the light is taken away?
Suggest a mechanism
that would explain the screen’s ability to glow after exposure to
c) Place your hand on the screen and once
again illuminate with bright light. Describe what happens after removing your
hand and the light.
d) Explain your observations.
e) Does the length of exposure have any
bearing on the glow?
f) Try different color lights, does this have
any effect on the glow? Can you explain your observations.
During the last phase of the learning cycle,
students apply the ideas developed during the concept development phase of
the cycle. Returning to the laboratory, they perform an experiment that
requires them to compute the potential and kinetic energies of an object as
it moves along a track. One method involves strobe photography
(see Heath Physics). A strobe
photo is made of a toy car as it moves down a Hot Wheels track. Analysis of
the photo provides information that may be used to compute the car’s
potential and kinetic energy at each point along the track. An alternate
approach uses apparatus such as a low-friction track, a photo gate and electronic timer.
In either case, the students discover that the
total mechanical energy is, for all practical purposes, conserved! As
student-produced graph indicates,
the total mechanical energy of the system
remains virtually constant throughout the motion.
As a second application activity, our students
take an excursion to Six Flags Great America. There they experience the
laws of physics operating on a grand scale. In particular, they view roller
coasters in a new light. They now see them as energy transformation
machines. Using triangulation, students measure the height of the roller
coasters. From this information they can compute the coasters' potential energy. Using the law of conservation of
energy, they proceed to determine the theoretical speed at various points
along the ride. Measuring the speed of the coaster, using distance over
time techniques, students estimate the frictional loses incurred during the
coaster’s trip by comparing gravitational potential energy at the beginning
of the ride with the kinetic energy near the end.
We have found the learning cycle approach to
teaching energy concepts to be very effective for a number of reasons:
Energy is a difficult concept. With
the learning cycle, students are provided the opportunity to deal with
objects on a concrete level before formal concepts are introduced. This is
in accordance with the precepts of Piaget and current cognitive research.
2) The learning cycle makes energy
meaningful. Students are made aware of the
importance of the energy transformations that
are continually going on all around them. Applications of material being
studied are intrinsic to the cycle.
3) This student-centered approach
encourages student engagement. Intriguing
manipulatives tend to get the most
disinterested students involved. Discrepant events leave students with a
need to know.
4) The energy learning cycle provides a
variety of kinesthetic learning
experiences. While turning the crank of a
Genecon, students really understand what is meant by “you can’t something
5) Using the learning cycle, you have an
opportunity to listen to the students dialog with peers and formulate
explanations. For me, this has always been one of the most exciting
aspects of teaching.
Chemistry and the Learning Cycle!
PDF files for
Learning Cycles on Energy
With this file
you can print off the individual stations and laminate them for numerous
uses and durability.
You'll need Adobe Reader to view files; get it here.
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