INTEGRATING
SIMULATION AND MODELING OF PREDATOR-PREY EXPERIMENT IN CLASSROOM
1.0
Introduction
Modeling
is a representation of an object, a system, or an idea in some form other than
that of the entity itself. A simulation of a system is the operation of a
model, which is a representation of that system. The model is amenable to
manipulation which would be impossible, too expensive, or too impractical to
perform on the system which it portrays. The operation of the model can be
studied, and, from this, properties concerning the behavior of the actual
system can be inferred. Simulation is operation in which a computer is made to
imitate a real life situation or a machine. It showing how something works or
will work in the future. Simulation simulate an activity that is
"real", and so it can be said that they are "virtually
real". Simulation is use as learning and teaching material because simulations can make these types of
interactive, authentic and meaningful learning opportunities. Learners can
observe, explore, recreate, and receive immediate feedback about real objects
and phenomena. Besides, simulation can develop their knowledge and conceptual understanding
of the content, gain meaningful practice with scientific process skills, and
confront their misconceptions. Example of simulation and modeling software that
teachers can use in teaching and learning is STELLA. STELLA offers a practical
way to dynamically visualize and communicate how complex systems and ideas
really work. STELLA supports diverse learning styles with a wide range of
storytelling features. Diagrams, charts, and animation help visual students
discover relationships between variables in an equation. In this simulation, I
will use predator-prey model sample as a material to help students understand
more on this topic.
2.0
Graph
1) Graph
1 - Normal (parameter=0)
2) Graph 2- Parameter (150)
3) Graph 3 - Parameter (600)
4) Graph 4 - Parameter (750)
2.1
Use of STELLA as a Motivator
The
motivational orientation (intrinsic or extrinsic orientated) of students have
significant impact on their learning performance. So, teachers must find a way
to increase student motivation. For example, the integration of simulation in
teaching processes. Simulations can be a motivator for learning. Instructional
simulations have the potential to engage students in "deep learning"
that empowers understanding as opposed to "surface learning" that
requires only memorization. Deep learning mean students can learn scientific
methods including the relationships among variables in a model. Simulation
allows students to change parameter values and see what happens.
Students develop a feel for
what variables are important and the significance of magnitude changes in
parameters. For example, in this STELLA experiment, students can change the
parameter of the predator-prey graphs. The parameters are set as 0, 150, 600
and 750. Students can actively involve in teaching and learning processes when
selecting the parameter values. They can change the parameter by entering data or by manipulating visual
objects to observe the consequences of
these changes via numeric displays, text labels and even changes in the
visualization environment. Then, from that they can formulating new questions
to ask. This
activity will gives students pleasure and develops their particular skill. They
will feel intrinsically motivated. Intrinsically motivated students are bound to do much better in
classroom activities, because they are willing and eager to learn new
material. Their learning experience is
more meaningful, and they can explore and go deeper into the subject to fully
understand it.
A
well done simulation is constructed to include an extension to a new problem or
new set of parameters that requires students to extend what they have learned
in an earlier context. The activity in class is highly effective and motivating
even for the whole student in the class. Teacher could starts with an
introduction where he or she can explains the relevant theoretical parts of the
complex problem. At least the roles and rules need to be clearly specified. The
students should understand the possible activities and consequences, which are
available in the simulation at the end. The exchange of experiences and a
discussion in small groups within or after the simulation help to increase the
understanding of the simulated reality. Students participate in an active and
motivating way, analyze information, interchange information among them, make
decisions and see the outcome of their actions.
2.2
Student’s Prediction from the STELLA graphs
While
it is not feasible to experiment with real predator and prey populations, it is
possible to generate data through simulations that model the interactions that
occur within a population, particularly between predator and prey. In daily
life, students do not have the opportunity to perform predator-prey experiments
because predator-prey is related to ecosystem and take longer time to observed
the process of the system. So, student do not have the experience about the
prey and predator relationship. This situation make the understanding of the
students in the classroom lower and make teachers hard to explain more the
topic. So, using the predator-prey experiment from STELLA software, it make
student understand because students can see the relationship between prey and
predator clearly using the graphs. From the graph teachers can help students to
understand the process of predator- prey. Students can use this simulation to
explore questions like, “what is the predation”. Prey and predator model are
arguably the building blocks of the bio- and ecosystems as biomasses are grown
out of their resource masses. A predator is an organism that eats another
organism. The prey is the organism which the predator eats. In this experiment
the predator is lynx whereas the prey is hares.
The
purpose of this simulation and modeling is to open the eyes of the students to
the idea that population sizes are always changing, and that there are many
different factors that can cause population levels to increase or decrease in size.
So, throughout the lesson students will be shown how many different factors can
influence population size with special emphasis placed on the differences
between density dependent and density independent factors. Students will become
engaged in the learning process through participation in an activity which
models predator/prey interactions over a 15 year period.
Teachers
can set the different parameter of the modeling to show student about different
type of relationship that can occur in real predator-prey dynamic . The
parameter are 0, 150, 600 and 750. The different parameter show the different
graph. The first graph is normal
parameter that is 0. Students should be able to describe the difference between
all graphs. The graph show straight horizontal line between hares and also
lynx. That means at this time the system is still maintain as there are no
threaten on hares. The ecosystem is still at equilibrium. In normal condition
of ecosystem the population of prey is usually more compare to the population
of predator. Hare population dynamics represents the number of hare in the
population at any point in time. This stock accumulates the flow of births and
net of the flow of deaths. The hares beget mores hares or in other words, hares
breed likes rabbit. The larger the population, the greater the birth flow. The
births flow is defined as the product of hares and their natality. Lynx eat
hare. This is the component of predator/prey interactions. The number of hares
killed per year is assumed to depend on hare density. The greater the density
of hares in the ecosystem, the larger the number of hares consumed lynx per
year. An increase in the number of hare
in the system propagates around the loop to lead to increase in the hare death
flow, and thus brings the number of hares back down again. Lynx birth process
parallels to birth process of hares. Populations are always changing. Sometimes
changes are the result of humans interfering with food webs or habitats. But
even when humans do not interfere, populations will still naturally shift up
and down or fluctuate.
For
further investigation, teachers can asks students about other graph. Then,
discuss with students possible explanations, leading students to understand
that the relationship of all the graphs. For example, teachers can ask students
to think critically about some question such as what are the limiting factors
that determine if an organism can survive in an environment and which
adaptations allow individual organisms to survive in this ecosystem? Students
can observe the graph and find the answer from the graphs. Students can run the
experiment for many parameters. When they run the experiment for several times,
students can make their own prediction about how the graph will look if the
other set of parameter is used. They will predict what will happen when they
decrease or increase the parameters. They will know that these three graph does
not show much different because the pattern in the graph show that the lynx
pattern closely follows the hares pattern. Only the amplitude for
each graph are different. For Graph 2 the amplitude for population of lynx is
higher than the amplitude for population of hares. But, for Graph 2 and 3 the number of hares and lynx
increase and decrease steadily. The hare level time shape shows the system is at
equilibrium until first five years time. This also is happen to lynx. Then the
hunting of hares upsets the system, and the population begins to oscillate with
pure sinusoidal time shapes. Every fifteen years the cycle are observed.
From graph it can be seen
that when the hare population went down, so the lynx population also went down,
but after that the hare population went back up, but much higher than the
equilibrium level. The lynx population lagged behind, but it also went back up,
also higher than the equilibrium level. The lynx population was large enough to
decrease the hare population, but that in turn caused the lynx population to
decrease, and so on. When the hare population goes up, the hare density goes
up. Every fifteen years, the hares reproduction rate increases. As more hares
are born, they eat more of their food supply. They eat so much food that they
are forced to supplement their diet with less desirable and nutritious food. As the hare population size grows, the lynx
population size begins to increase in response. The lynx got enough nutrient
from eating the hares. Because there are so many hares, other predators
opportunistically begin to hunt them along with the lynxes. Many animals hunt
hares but none with the efficiency of lynx. Lynx are the ultimate hare
specialists and as such their fortunes rise and fall with those of their
big-footed prey. And they have kept pace in the evolutionary race for survival
because their huge furry feet and long hind legs allow them to run and cut on
top of snow. Yet they still can’t kill all the hare. Because of the hunter the
hares less nutritious and varied diet begins to have an effect, the hares begin
to die due to illness and disease. Fewer hares are born because there is less
food. The hare population size begins to go into a steep decline. Therefore,
the lynx population also begins to decline. Some lynxes starve and others die
due to disease. Both the lynx and hare populations have fewer babies and this
decrease in population gives the vegetation a chance to recover. Once there is
enough vegetation for the hares to begin to increase their population the whole
cycle begins again. In order to maintain hares population at equilibrium, the
lynx population must increase or they must become more efficient( increases)
predators. These linkages are the prime movers of energy through food chains.
They are an important factor in the ecology of populations, determining
mortality of prey and birth of new predators. Predation is an important
evolutionary force because natural selection favors more effective predators
and more evasive prey. Disease, food supply and other predator are variables in
this complex relationship. Other than that, the lack of hiding places for the
hares affects the lynx. If there are many hares, and few hiding places, and the
lynx will be well fed and healthy, but if the hare population falls the few
remaining hares will be well hidden and
the lynx will be sickly and die young. They deal with the general loss and win
interactions and hence may have applications outside of ecosystems.
For
the fourth graph, teachers can encourage students to make their own
observations and prediction of predator-prey relationship and share their
findings in class because the fourth graph that is 750 parameter, the graph
also seem like second and third when there are increasing in hares also make
the lynx increase. But the only different of this graph from others is that the
amplitude of graph that describe the population of hares show much increasing
compare to lynxes at the end. The population of hares also decrease much than
lynx every fifteen years. The lynx population increase and decrease steadily
with lower amplitude than population of hares. Each population has a boom
pattern when there are too many lynx or hares for the available resources and a
bust pattern when many hares or lynx die and very few are left. A higher
density of hares means fatter, happier, and longer-lived lynx. On the other
hand, as the population density of hares declines, a larger portion of the lynx
population will die of malnutrition and starvation. In addition, the flux in
this cyclic relationship is what allows for the ecosystem dynamic to work.
Without flux, vegetation wouldn’t have a chance to recover from the hare
population’s continuous eating, and without vegetation, the hare population
could no longer exist in its habitat. Therefore neither could the lynx
population that depends upon the hare population for food. The increasing of
hares at the end is maybe because of the survival characteristic that they
have. When seemingly competitive interactions are carefully examined, they are
often in fact some forms of predator-prey interaction in disguise. This forces
the prey to adapt to avoid consumption. Quite simply, organisms are driven to
survive, so prey animals respond over time with physical and behavioral
adaptations to all the natural forces and conditions that conspire to kill
them. In other words, the individuals who are better at avoiding consumption,
live on. Natural selection has equipped hares with outsized hind legs and feet
to run at lightening speed over snow. Their huge ears magnify the slightest
sounds. Hares have developed a natural camouflage and change color with the
seasons which is white for winter and brown for summer. With so many things
trying to eat them, they need lots of defensive weapons. This represents the
very real fact that if there are large numbers of hiding places for the hares
to escape predation, a large number of hares per hectare will not result in a
much better food supply for the lynx. The bottom line is that ecosystems are
complex. The hares that live longest and have the most babies pass more of
those successful genes to the next generation, refining the traits over time,
like camouflaged fur, that allow hares to escape lynx. This ensuring the
survival of the species and its competitive to adapt to dynamic landscapes and
dozens of hungry predators. With a prey population that is becoming better at
avoiding consumption, the predators must also adapt to become more efficient.
Predators respond in kind with adaptations that allow them to exploit
particular prey species. Otherwise neither would survive. The individuals who
cannot capture any prey die off, and the better adapted population lives on to
pass on their traits. This continues in an evolutionary predator-prey cycle.
At
the end of the lesson, teachers should make a reflection about the teaching and
learning when using the simulation. The simulation guide teachers to reflect on
the analogy after using it in the classroom, considering whether or not it was
useful and possible improvements for the future. Compared with the laboratory
investigation approach, our simulation to this predator-prey topic has resulted
in a positive shift toward helping students understand the mechanism of natural
selection. It provides a scaffolding
tool to help students make the conceptual leap to basic natural-selection components.
To understand a mechanism is to be able to simulate the events or processes in
one's mind and then use that mental model to make predictions in novel
situations (Chart, 2000). This simulation provides an experience to which
students can mentally refer when thinking about natural selection.
3.0
Conclusion
As the conclusion, computer simulations such as STELLA have the
potential to enhance the way of the teaching and the students learning. It is
suitable for teacher to use it in
school. They allow teachers to bring even the most abstract concepts of life
for students and incorporate otherwise impossible or impractical experiences
into teacher daily instruction. This predator-prey modeling help us to
know about the predation in real
ecosystem. From this model, the learning become more interesting and the
information getting is more deep. Students can know very well the real process
happened in our ecosystem about this type of predation. Students often feel
that predators are “bad” because they kill smaller, weaker animals for food.
Modeling the effects that predators have on habitats can help students realize
that predators are not bad and that they play an important role, or niche, in
maintaining stable communities. Additionally, from this simulation and
modeling, students will gain scientific habits-of-mind (such as the ability to
visualize, contemplate, and explain complex concepts and phenomena) that are
both encouraged in the recent reform documents and necessary for future careers
in science.
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