1.0 INTRODUCTION
A simulation of a system is the operation of a model of the system. The model can be configured and experimented with, usually, this is impossible, too expensive or impractical to do in the system it represents. The operation of the model can be studied and hence properties concerning the behaviour of the actual system or its subsystem can be inferred. In its broadest sense, simulation is a tool to evaluate the performance of a system, existing or proposed, under different configurations of interest and over long period of real time.
Simulation is a modelling and analysis tool used for the purpose of designing planning and control of manufacturing systems. Simulation may be defined as a concise framework for the analysis and understanding of a system. It is an abstract framework of a system that facilitate imitating the behaviour of the system over a period of time. Simulation models can also be used to observed a phenomenon that cannot be observed at very small intervals of time. Simulation can also stops continuity of the experiment.
Simulation modelling techniques are powerful for manipulation of time system inputs and logic. They are cost effective for modelling a complex system and with visual animation capabilities they provide an effective means of learning, experimenting and analysing real life complex systems. Simulation are capable of taking care of stochastic variable without much complexity. Besides, simulation can develop their knowledge and conceptual understanding of the content, gain meaningful practice with scientific process skills, and confront their misconceptions.
2.0 STELLA SOFTWARE
STELLA software is used as a medium to run the simulation. 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.
Steps to Constructing a STELLA Model:
1. Constructing a Model
2. Parameterizing the Model
3. Exploring Model Dynamics
To prove the effectiveness of simulation and modelling in teaching and learning process, STELLA offers a practical way to dynamically visualize and communicate how complex systems and ideas really works. Whether they are first-time or experienced modellers, teachers, students and researchers use STELLA to explore and answer endless questions. STELLA models allow you to communicate how a system works, what goes in, how the system is impacted or what are the outcomes. STELLA supports diverse learning styles with a wide range of storytelling features. Diagrams, charts and animation help visual learners discover relationship between variables in an equation. Verbal learners might surround visual models with words or attach documents to explain the impact of a new environmental policy.
STELLA is used to simulate a system over time. The sentences bring the meanings that students may predict what will happen next for the experiment. It will trigger students to think more about what will happen next in the experiment if they increased the data. Then STELLA can be used to jump the gap between theory and the real world. In this case, students can observed clearly what happen to the data or experiment that have been done compared to only know the theory of it during learning process. They can relate the theory that had been learned with their real life. Students will have more idea about how this thing work compared to only learning the theory.
We employ STELLA modelling in combination with investigative exercises and experiments. The modelling helps students develop hypotheses, explore predictions, summarize experimental results, and extend their results to novel scenarios. STELLA provides the flexibility to allow students to model a variety of experimental systems and the power to provide for meaningful outcomes that relate to specific biological content
3.0 DISCUSSION
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.
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.
Teachers can set the different parameter of the modelling to show student about different type of relationship that can occur in real predator-prey dynamic . The parameter are 0, 300 and 700. The different parameter show the different graph.
Graph 1 : 0 size of time lynx harvest
Graph 2 : 300 size of 1 time lynx harvest
Graph 3 : 700 size of 1 time lynx harvest
The graph above is the result obtained from simple prey-predator dynamics experiment. The graph shows the relationship between the number of hares with the changing in number of lynx. The hares are prey or food source for lynx and the lynx is the predator. In graph one, when the default is zero for the removal of lynx, we can see a stable system, with both lynx and hare in a balance such that for each population, birth is offset by deaths.
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.
In the second graph, when the default is 300, the graph became unstable. In the third graph, we can see that the graph became more unstable. When the number of lyxn decline, the number of hares also decrease rapidly. Shortage of prey means that the predator has to compete among each other for food. That is why we can see from the graph, at certain time the number of hare also decrease. When the number of predator increase, slowly the number of prey also increase.
By using STELLA software, students will be more motivated to explore the experiment on their own. This is one of the reasons why learning through simulation or model is more effective. Students can explore on their own and try to predict what will happen to the situation. From the patterns of the graph obtain, students can make their own prediction or conclusion to what will happen to the number of lynx and hares whether it will increase or decrease. When they can explore more in what they had learn, they will become more motivated to explore that thing. In other words, their intrinsic motivation is increase while using this simulation.
By using simulation, students can decrease the gap between the theory and real world. What they already learned in class about the theory of prey- predator relationship, they can see the result through this simulation. Even though the parameters change to a bigger size of number, students still can make their prediction regarding the outcome. What conclusion that can they make is that, the greater the density of hares in ecosystem, the larger the number of hares consumed per lynx per year. Without running the experiment by themselves or not in the real place for the experiment, by the simulation only they may not what happen at the real places. Students can predict that a lighter density of hares means fatter, happier and longer-lived lynx. That is why the pattern of graph obtain is like the graph above. Other than that, as the population density of hares decrease, a larger portion of the lynx population will die of malnutrition and starvation.
4.0 ADVANTAGES AND DISADVANTAGES OF STELLA
4.1 Advantages of using STELLA:
One of the advantages of using computer simulation like STELLA software is it offers the opportunity to experiment with phenomena or event, which for a number of reason, cannot normally be experimented in traditional way. Bork (1981) points out: ‘simulations provide students with experience that may be difficult or impossible to obtain in everyday life. Compare to traditional way, the only thing teacher can do is to discuss the nature and content of the system without experiencing themselves. It is certain that experimenting be useful because this is generating an insight into the functioning of economic system.
Other than that, computer simulation can be used in education to give the student more feeling for reality in some abstract fields of learning. From Foster (1984), ‘simulations can be entertained because of dramatic and game-like components’.
Besides that, bonus for the teacher to explain a difficult interrelationship such as hybridization experiment with fruit flies. It is difficult to explain in traditional way that will fail for student to understand better. Execution of the real experiment is impossible because this would take a number of weeks and cannot be integrated as such within a lesson. By using a simulation experiment, it is a chance for student to understand better the relationship such as hybridization experiment.
Simulation is especially useful if changes in an existing system are to be made, and the effects of the changes should be tested prior to implementation. Trying out the changes in the real system may not be an option, because the system does not yet exist, the costs are too high, there are too many scenarios to test, the test would take too much time (weeks, months, years), the changes are not legal, etc. In all these cases, a simulation model allows to test various scenarios in often only a couple of minutes or hours.
4.2 Disadvantages using STELLA:
Simulation software also brings us to disadvantages. A first advantage is simulation error. Any incorrect key stroke has the potential to alter the results of the simulation and give the wrong result. The programming using theories not often 100% correct. In order for the simulation to be accepted in general community, it must have to take experimental results and stimulate them. If two data sets compare, any simulation already design will have some credibility.
Another disadvantage is that it can be quite expensive to build a simulation model. First, the process that is to be modelled must be well understood, although a simulation can often help to understand a process better. The most expensive part of creating a simulation model is the collection of data to feed the simulation, and to determine stochastic distributions for example in processing times, arrival rates and others.
In addition, disadvantage for simulation in comparison to exact mathematical methods is that simulation cannot naturally be used to find an optimal solution. There are methods which long to optimize the result but simulation is not inherently an optimization tool. Simulation is often the only means to approach complex systems analysis. Many systems cannot be modelled with mathematical equations. Simulation is then the only way to get information at all.
5.0 Can STELLA software use for teaching and learning in school?
STELLA software can be used for teaching and learning in school because it provide a fertile learning environment for students. The use of simulated activities in education is widely becoming recognized as an important tool in schools. One of the reason why STELLA software can be use in school is it is easy to construct. Besides that, simulation can be paused, whereas real life cannot. Pausing allows more time for students to assess what’s going on and they can think on what happen. Although to build simulation software need a lot of money but it often cheaper to create than their real life counterparts. Installing flight simulation software is cheaper than buying a practice jet for each school.
Student’s interest more toward element of graphic and dynamic. Simulation is very suitable to attract students to learn something. Other than that, it encourages student to be trigger to learn especially in science. They will get an experience by itself through simulation without the need to watch the real thing.
With STELLA software, student can try a lot of experiments in many times over. They can adjust the parameter and see the pattern of the experiment. Simulation increasing the student interest in learning the lesson. Student will more excited and always want to know on what happen. They also can do the experiments that are impossible to do in real experiments.
In addition, the bonus for school that have simulation software because they are not necessary to buy an expensive experiment tools. Teachers just teach the student by using the STELLA software. It is because some of the experiment tool is very expensive and sensitive. It expose to damage. Student will not bored if the experiment if fail because with STELLA software they just reset and run again.
6.0 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 modelling 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. Modelling 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 modelling, 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.
Stella software makes the learner learn with interesting and meaningful learning. An attractive, dynamic and can run easily makes the learner more excited to explore with this simulation software.
I think it is one of the other alternatives to attract the student to learn in many subject especially for science subject that required thinking critically and make the relationship with each other.
By teach using STELLA software, teachers can focus on the learning objective and the content. Students also use the inquiry and constructivism approach and at the same time it fulfilled the requirement by government that brings forth good students in critical thinking capabilities.
