Assignment 4

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.