Programs based on Parallelism and/or the Parallel Instruction theory

(applications, instruction, exercises and/or manuals)

There are also an old list of products (mostly Mac-based) and a new list of products (mostly web-based) about my educational simulation applications.

Economical stuff:

ECONOMY (Mac and web versions)

This program is based on a complex small open economy model (the Netherlands) of Dr. Miltenburg. It is a product of Enschede UT in cooporation with the Rotterdam University (EUR) and the University of Moskou, 1995)

The program covers:

  • The Dutch economy and in particular macro-economics;
  • Which parameters can be used for this learning and training environment?
  • Which variables are important for insight or training in this field?
  • What are the most important educational aspects of this simulation programs?

  • Economics teaching deals with concepts that are described in a purely quantitative way. Abstract and rather complex mathematical models of economic systems are important in teaching topics from micro-economics (e.g. the relations between profit, demand, cost, production level and price) as well as in teaching topics from macro-economics (e.g. the behaviour of the national economy in pursuit of measurements changing parameters like taxes, national product, employment or government budget). The relations are usually described in the form of discrete mathematical formula. An aptitude for mathematics and abstract thinking is a prerequisite for understanding these relationships. With regard to this prerequisite economics teaching can be compared with chemistry and physics teaching.

    In practice the models are usually taught in a purely theoretical way in economics teaching. However, according to many learning theories a phase of active experimentation, enabling the students to gain personal experience, is essential for the construction of an adequate mental model by the students. The necessity of active experimentation is one of the main motives for the introduction of experiments with systems kept under controlled conditions in the physics curriculum and in the chemistry curriculum. However, experiments with economic systems similar to the practical work that is done in science teaching, are not possible.

    The application of computer simulations of economic systems for educational purposes may be a means to overcome this problem. By using such a computer program, the student can learn the operation of economic mechanisms in a very active way. He or she will get a continuous feedback on the decisions that he or she makes based on his hypotheses about the operation of the economic system, enabling him to perfect his mental model based on (almost) concrete experience.

    Simulations of economic systems can be used in a game-like context. When this approach is followed, the student is allowed to control the simulated system (e.g. a commercial enterprise or the national economy) in order to achieve a predestine commercial or political goal (like maximizing the profit of the enterprise or minimizing unemployment or reducing the deficit of the government budget). In this way models of economic systems, otherwise considered complex and abstract by the students, can become as fascinating as video games. The interaction with these game-like simulations can have two positive effects on the students: an increased motivation to learn and the gain of (almost) concrete experience, which is hard to gain in any other way. Because of these features, the effect of an economy course might be substantially improved if educational computer simulations are used. However, a danger exists when economic simulations are used in a game-like context. Students may fall into the trap of 'game-playing' rather than simulating rational real-world behaviour (as pointed out by Stanford, 1972). The presence of an observant teacher, aware of this danger, is a prerequisite in order to prevent the students from falling into this trap.

    Chemical stuff:

    CHEMISTRY (Mac and web version)

    This simulation models chemical reactions in a laboratory setting. CHEMISTRY simulates titration experiments. The titration of acid solutions by means of bases can be simulated as well as the titration of basic solutions by means of acids. The simulation of strong acids and bases is possible as well as the simulation of weak acids and bases. The model on which CHEMISTRY is based has been derived by van Schaick Zillesen and Min from general theories about acid-base equilibria. CHEMISTR is designed in order to enable students to practice the skill to determine the properties (strength, pKa, pKb) of solutions of acids and bases by titration with standardized acids or bases. Furthermore, students may use the program to exercise two skills:

  • the skill to calculate the pH of a solution of which the original composition is known after the addition of known quantities of standardized solutions (acids, bases or water).
  • the skill to recalculate the original composition of a solution of which the pH and the quantities of standardized solutions added to it are known.

  • The simulated experiments can be executed very accurately because drops of acid or base can be added to the solution one after another. The speed of the chemical reactions is retarded in the simulation. For this reason it may take some time before the reaction caused by the addition of a drop of acid or base is completed. This dynamic aspect may facilitate the discrimination of the chemical reactions causing the observed phenomena. Furthermore, time registrations of the pH, the pOH, the concentration of cation of base, the concentration of anion of acid, the concentration of non-ionized base and the concentration of non-ionized acid are provided for in the simulation. In a real laboratory this complete information can only be attained by means of expensive ion-sensitive electrodes.

    CISTR (Only in Dutch)

    This simulation program CISTR, is a Continuous Ideal Stirred Tank Reactor. This program is made by Kamperman of the faculty Chemical Technology of the University of Twente.


    This simulation program is based on a mathematical model of the Pasteur sterilisation process in the milk. With this program a user can learn the basic processes in the milk for making cheese.


    This program is a simulation of a chemical plant (AKZO Holland). For the chemical company AKZO Hengelo, the University of Twente developed a computer simulation program named BRINE PURIFICATION (Van Schaick Zillesen, 1990). This program is based about a mathematical model of the complete chemical plant for brine purification of the local mining industry. In the dynamic processes on the screen the trainee can intervene by clicking the mouse in 'in-click regions' or else with the help of pull-down menus.

    The brine purification process is a relatively slow process. Usually it takes several hours before the consequences of an intervention in the installation (e.g. changing the flow of one of the components introduced in the process) can be observed. For this reason it is hard to get a good understanding of the reactions of the process in on-the-job training, because in the meantime the team of operators making the intervention may be replaced by another team. Furthermore other disturbances may have occurred, causing the operators to make new interventions. For this reason it is hard to study the influence of an intervention independently.
    The educational simulation, which proceeds with a speed of approximately 1000 times real time enables the operators to get a quick, direct response that can be studied independently. For this reason operators may get a better understanding of the processes in the brine purification installation if they are able to experiment with the educational simulation program.


    This program is developed with MacTHESIS, version 5.0 experimental with "desktop video feedback messages". QuickTime must be installed in order to use this version of COAGULATION. The program can simulate coagulation in milk ('stremmen'). With this milk cheese is making. There are one 'text-message' and three 'video messages' in this program:

  • there is a text-message if nothing is done within the program; that means the student hasn't intervened in the model.
  • there is a video-message if you have put enzyme into the milk-vat
  • there is a video-message which indicates that coagulation has not yet occurred
  • there is a video-message which appears when coagulation has occured

  • Medical stuff:

    (these programs are for medical students)

    CARDIO (Mac and web versions)

    This program is a simulation program to study the control mechanisms of human bloodpressures. The program CARDIO simulatates the blood pressure regulation under normal and abnormal conditions. The model underlying this program allows the simulation of pathological conditions, such as myocardial infarct, renal artery stenosis or renal insufficiency. Therapeutic interventions in abnormal conditions can also be simulated. The program allows the application of drugs like cardiac glycosides, diuretics or vasodilator. It is based an a model developed by T.Coleman, USA.

    The computer simulation program CARDIO enables students to experiment with the basic principles of blood pressure regulation for a healthy young man. The program simulates an experimental laboratory where hemodynamic research can be done, variables can be registered, and where interventions in the model can be made without real-life complications. The computer simulation program CARDIO is often the first moment in the curriculum in which the student can check his or here understanding of human circulation in the context of realistic problems. With this computer simulation program the student can do a series of experiments, such as the simulation of heart failure, hypertension, renal failure, exceptional blood loss, selective venous constriction, and selective arterial constriction. These interventions can be selected by the student or chosen as a case by the teacher. When it is presented as a case the student can be asked to form a diagnosis and operate therapeutically, starting the hemodynamic picture on the graphical screen. The student has the possibility to introduce medicines like heart glycoside (digitalis), vasodilator, diureticum, sympathicolyticum, or noradrenaline.


    Thisis a simulation program of the effects of lack of water and electrolites on a human body. Students can add fluids to the body. The mathematical model underlying this program contains over 200 variables and describes control mechanisms of body fluid volumes and electrolytes as well as respiratory control mechanisms. This model allows a variety of simulations of e.g. thirst, fluid loss, exaggerated drinking, carbon dioxide inhalation, severe physical exercise, etc. The student can again infuse fluids of different compositions, give a diuretic, etc. The basic physiology of respiratory and metabolic acidosis and alkalosis can be studied with this model. It is based an a model developed by Ikeda et al, Japan.

    The computer simulation program FLUIDS enables students to experiment with a model of the human water and electrolyte system and the regulation of respiration and its underlying (basic) physiology and pathophysiology. The simulation consists of the following: heart and cardiovascular system, lungs, intra- and extra cellular fluid compartments, nerve reflections, the kidney, and a number of hormonal systems with an influence on the kidney function. In some ways this simulation coincides with the model of the computer simulation program CARDIO, but in several important parts it is much more extensive. The computer simulation program FLUIDS simulates a kind of experimental laboratory environment, so that students can do research on water and salt regulation and the regulation of respiration under various circumstances.

    (Mac and web versions)

    In early phase of their studies medical students can familiarize themselves with some basic concepts from hemodynamics and some aspects of arteriosclerosis. In using this program an answer is given to questions like:

    'What happens if the total peripheral resistance of the circulation is increased?' The opposite can also be an educational goal, namely the question as to what is the cause of the deviating picture of the diastolic pressure in the aorta. 'Can the cause of a decreased diastolic pressure in the aorta be a decreased compliance of the aorta? Yes or no?'

    Students learn to handle notions like compliance and total peripheral resistance and changes there in. Students are supposed to be able to formulate questions and/or hypotheses and to verify these hypotheses with the help of this simulation program. Within the framework of a course about arteriosclerosis, case studies has been developed about the hardening of the wall of the aorta and the increased total resistance of the peripheral circulation. In this case study the students themselves have to recognize that the mean peripheral stream has changed and they have to try to restore it by adapting the pressure of the ventricle. The program is intended to teach the students how to deal with basal hemodynamic relations such as between pressure, compliance and volume and those between stream, resistance and pressure and to determine the consequences of interventions in hemodynamic variables.

    The aorta is the great artery which springs from the left ventricle in the heart. The heart pumps (with a certain pressure) a quantity of blood through the human body with each heart beat attended by a change in pressure in the aorta. The aorta itself is elastic. The quantity which plays a role in the elasticity of the aorta is compliance. There is a connection between the form of the changes in pressure in the aorta and compliance. Furthermore there is a connection between the blood pressure in the aorta, the quantity of blood which flows through the aorta and the resistance offered by the body (the peripheral resistance). The interesting variable to be measured externally, 'the pulse pressure', is practically equal to the pressure of the aorta. This pressure varies considerably and is very characteristic.


    This program simulates the growth of two kinds of single-celled organisms in laboratory cultures. The organisms compete with one another over limited resources. This model is from Lotka, A.J. (1925). Elements of physical biology. Williams & Wilkins, Baltimore. (Reprtinted as: Elements of mathematical biology in1956 by Dover, New York). A more modern treatment can be found in: Pianka, E.R. (1978). Evolutionary Ecology. Harper & Row. New York. The application contains five cases: competitive exclusion, stable equilibrium, symbiosis, fragile equilibrium and a steady state simulation about a monoculture of species 1.

    (Mac and web versions)

    This program is a simulation of the two-compartiments model from farmacokinetics. The program is exclusively meant for demonstration purposes. The program have three ways of administering drugs: intravenous, infusion and intra-muscular.



    This program is based on a model of the insuline and glucose mechanismes in the human body. It is a product of the University of Twente in cooporation with the University of Leiden (RUL) (Toegepaste Biologie) (1993). You see the influence of eating in the morning, the lunch and the diner; plus in the morning some cookies.

    (Mac and web versions)

    More than fifty years ago action potentials were first recorded by means of external electrodes by Hodgkin and Huxley. Based on the results of their experiments they designed a new revolutionary theory about action potential generation which meant a breakthrough in electrophysiology at the time. In 1952 Hodgkin and Huxley published a quantitative model of the electrical and electrochemical phenomena in the environment of the membrane of a nerve fiber based on their theory. The original model of Hodgkin and Huxley was not a mathematical model but an electric circuit consisting of capacitors and resistors. however, it is very simple to transfer this model into a mathematical model.

    The prototype AXON is based on such a mathematical model. Although some of the aspects of the conductivity of the cell membrane were not described correctly by Hodgkin and Huxley, their model is still very useful for the education of medical students and biology students as it can be used as a simplified version of the correct model thus helping the students to build a conceptual 'framework' model which can be filled with the complete and correct conceptual model in a later phase of their education. It can also be used as a demonstration for the experimental research techniques used in cell physiology.

    Ecological stuff:

    (made for biology class secondary school)

    (Mac and web versions)

    This program is a simulation program of how pray and hunter can influence each others lives. It contains a prey-beast /predator model. The program is a simulation of a small tundra ecosystem consisting of lemmings, foxes, and grass. It is based on a model developed by P. van Schaick Zillesen.

    On the arctic tundra strong fluctuations occur in the numbers of lemming, predators and herbs. At the end of years with extremely high densities (outbreaks) of lemmings all the plants are eaten causing starvation of most of the lemmings. Years with outbreaks of lemming are usually followed by years with extremely low densities.

    After an outbreak of lemmings it will usually take three or four years before the next outbreak occurs. Fluctuations of predators like arctic foxes, which are dependent on lemmings as their main source of food, usually show the same pattern as the lemming fluctuations (with some delay). Schultz (1969) described the relations between lemmings, their food (herbs), their predators (mainly arctic foxes) and the bottom of the arctic tundra. He emphasized the role of changing nutrient concentrations in the dynamics of the arctic tundra system. In the spring of a year with an outbreak of lemmings almost all minerals are present in the herbs. However, as a result of the consumption by the rodents most of these nutrients are deposited on the surface of the tundra in the form of faeces during the same year. The next year plant growth is minimal because of the low nutrient concentrations prevailing in the soil. It will take several years for the faeces to mineralize because of the extreme polar climate. However, the third year after the outbreak the mineral level of the tundra soil has gradually increased to a point that enables rapid plant growth. However, the nutrient level in the crop is still very low during this year. A high nutrient level in the crop, enabling a good lactation in lemming females, is required in order to cause a lemming breeding success. For this reason the number of lemmings does not rise proportionally to the plant growth during this year. However, during the next year the nutrient concentration in the herbs is much higher causing a new outbreak of lemmings. The program LEMMING simulates the processes described above. The model on which the program is based has been developed as part of this study and has so far not been published anywhere else.

    (Mac and web versions)

    Fish ponds are widely used by man for food production. The management of a pond; affects the entire ecosystem, including fish, nutrients, zooplankton, benthos, dissolved oxygen, microorganisms etc. A high efficiency of fish breeding can be achieved only with optimum values of the control parameters of the pond, like the input of fertilizers, the re-aeration of the water in case of oxygen depletion and the addition of artificial fodder. Svirezhev et al. (1984) developed optimum control strategies for a fish pond ecosystem. As part of their study they constructed a mathematical model of a fish pond. Van Schaick Zillesen designed and realised the computer simulation program FOOD CHAIN (VIJVER) with a lot of instructional support (also on MS.DOS with the THESIS system) for de Stichting Leerplan ontwikkeling (SLO, National Institute for Curriculum Development) in cooporation with Hartsuiker et al. (Dutch version).

    Due to the relatively simple tropic structure a fish pond can be an excellent case for the study of the characteristics of food-chains and ecosystems in general. However, fish ponds can not be studied in the biology curriculum for practical reasons (space and time). A computer simulation program, simulating a fish pond can be an excellent tool to overcome these problems.

    For this reason a mathematical model of a fish pond can serve two purposes: fish pond management and education. The model constructed by Svirezhev et al (1984) simulates a fish breeding pond in which three fish species are present: carp, silver carp and bighead carp. Van Schaick Zillesen adapted the model for a pond in which only two fish species are present (carp and silver carp).

    The program FOOD CHAIN is based on the adapted version of the model of Svirezhev et al. Svirezhev et al. (1984) give values the parameters used in their model. However, they do not give starting values for the variables of the model. Labordus (SLO) gathered the data about the values of these variables from literature.


    This simulation models the growth of grain in Zambia. It is based an a research model developed by H. van Keulen (from the University of Wageningen and connected at ITC, Enschede). It is a training program for students and pupils in argriculture.

    Technical stuff:

    (Mac and web versions)

    The computer simulation program BOILER was developed by a graduate student at the faculty of Educational Science and Technology at the University of Twente. During the development there was cooperation with staff members of the Stichting voor de Leerplanontwikkeling (Foundation for the development of curriculums) Enschede of the project Alternatieve Energie (alternative energy) in elementary vocational education. The computer program is available for Apple Macintosh and MS.DOS computers.

    The computer simulation program BOILER enables students to become familiar with the characteristics of a solar boiler and to gain insight into the influences of different interventions in the model around the installation. The model simulates the working of a solar boiler installation consisting of a collector, a storage vessel, a heat exchanger with a pump which runs through the collector and storage vessel and a possibility for tapping. Intervention is possible in the model. For example, students can change the intensity of the sun-rays or the heat capacity of the collector. The students has two screen pages at their disposal. One page with a visualized representation of the underlying mathematical model of the solar boiler installation and a page graphically representing the temperature of the heated water.

    The target group for the computer simulation program BOILER are students of elementary and secondary vocational education. The object is that the students increase their insight into the working of the installation and its characteristics while working with the program. That is why the students should already have some theoretical knowledge with regard to the solar boiler. So the program can best be used in e.g. a course in which theory is dealt with first. After that they are introduced to the characteristics of the installation through a real solar boiler installation. Finally the students can increase their insight into the working of the installation with the computer simulation program by experimenting with all sorts of interventions which are not possible with a real installation. Three cases have been developed in the computer simulation program BOILER with which the students can practice with the characteristics of the installation in special situations.

    (Mac version only)

    This program is based on the laws of thermodynamics. Simulations based on the Boyle Gay Lussac model are very illustative for students, just like this simulation application.

    (Mac and web versions)

    Many mathematical models of a transistor are known. Some of these models are matrix-models, treating the transistor as a black box, presenting sets of values of output variables as a result of sets of values of input parameters like input impedance, voltage gain etc. Other models simulate the transistor in a more transparent way. In these models, the transistor is described by means of an electronic circuit. The models can be used in order to study the transistor's behaviour in a dynamic way by changing the parameters. The model of a transistor, implemented in the prototype TRANSISTOR, belongs to the second type of models. It describes the behaviour of a transistor in a normal low signal amplifier circuit. The model has been developed for educational applications by Min and Malhotra (1988) and Min and Van Leeuwen (1990)

    Mathematical stuff:

    REEKSEN (Mac and web versions)

    This program is based on a model from R.D. Carmichel en E.R. Smith of the Taylor equations. It is a product of the University of Twente in cooporation with the University of Delft (THD) (1985). The contents are: sinus(t), exp(t) and ln (1 + t).

    CHAOS (Mac and web versions)

    This program is based on a model from Lorentz: the Lorenz equations for chaos. It is a product of the University of Twente in cooporation with the University of Delft (THD). The contents are the 3 differential equations of the model of Lorentz.

    INTEGRATOR (web versions)

    This program is based on the integration equation. It is a product of the University of Twente for our e-books about integration (2002).

    KAPITAAL (web versions)

    This program is based on a conceptual model about the flow of capital. It is a product of Rik Min himself (2005).

    Animation stuff:

    PLC, a programmable logical controler

    This program is based on the programmable environement of a PLC. It is a interactive Multimedia product with 'modelling' aspects. The most important output is an linear animation of a special industrial 'PLC-driven' robot with 9 'model-driven animation objects' (built with CAILIB). It is a simulation product of the University of Twente in cooporation with the Stichting Leerplan Ontwikkeling (SLO) te Enschede (1985) (Wolters, van Doorn and Min, 1985-1990)

    PADDLE (web versions only)

    This program is based on an idea from the Max Planck Institute (D). We develop this formula-driven animation with 'eys' and 'paddles' for an illustation of an 'intelligent' animation object for our lessons and our e-books.

    PLANET (web versions only)

    This program is based on a simple mathematical model. We develop these applications for an illustation of an forumula-driven animation for our lessons and our e-books.

    BALL (web versions only)

    This program is based on a simple mathematical model. We develop these applications for an illustation of an forumula-driven animation for our lessons and our e-books.

    Enschede, 1985 - 2012